The countdown to the 2023 Heze Auto Show began, and thousands of models gathered together, and the tickets for the exhibition were quickly picked up!

The 5th China (Heze) International Future City Automobile Exhibition 2023 was held in Heze International Convention and Exhibition Center from April 14 to 18, 2023. This five-day auto show will provide a stage for all automobile brands to show their elegance.

Ticket collection channel for participation →

Ticket collection channel for participation →

Welfare! Welfare! Welfare, it’s coming! Blessed are the riders who are ready to participate in the exhibition. Now the last 2000 free exhibition places have been prepared for everyone. Those who want to come to the exhibition, see the cars and buy cars, remember to collect tickets! If it’s late, it won’t be!

The main change in appearance of the new Song Pro DM-i is the design of the front grille. The whole grille is larger in size, and the chrome-plated short-line element combination is adopted inside. The matte trim on the top is consistent with the cash, and the middle is the model "Song". The headlights on both sides glow with purple, which looks quite exquisite. At the same time, the new car has also upgraded the air intakes on both sides, making it bigger and more exaggerated, and making the whole car look more dynamic.

The rest of the design of the car body is basically the same as that of the cash. The classic through taillight design is adopted, and a large area of black grain decorative board under it is both durable and practical.

The size of the new car is longer and higher than the current one, with the length, width and height of 4738×1860×1710mm and the wheelbase of 2712mm respectively. In terms of power, the new car is still equipped with a 1.5L+ hybrid system, with a maximum power of 81kW and a maximum motor power of 145kW, and the overall power performance is good.

No matter whether you want to see a car or buy a car, hundreds of popular models at the scene are greatly reduced in price, and the models are whatever you choose. There is only one distance between you and your car. Now get the tickets, and have a zero-distance contact with your car at the auto show!

The article has also prepared the exhibition tickets for everyone, and you can pick them up with your fingers!

Ticket collection channel for participation →

Mercedes-Benz Shanghai Auto Show made a big move: 13 first/listed cars

On April 18th, the 20th Shanghai International Automobile Industry Exhibition will open soon.Mercedes-Benz will present a lineup of 27 heavy-duty models with one world premiere, five China firsts and seven China-listed models at Hall 4.1 of the Shanghai International Auto Show.. All brand matrices of Mercedes-Benz, Mercedes -EQ, Mercedes-Maibakh, Mercedes -AMG and G-class off-road vehicles under the Trident Star Emblem are assembled.

  Three latest Mercedes-Maibakh products covering pure electric, hybrid and high definition will be released soon. Mercedes-Maibakh’s first mass-produced pure electric vehicle, the new Mercedes-Maibakh EQS pure electric SUV, will make its world debut during the auto show. Mercedes-Maibakh brand’s first plug-in hybrid car-Mercedes-Maibakh S 580 e plug-in hybrid car, and Mercedes-Maibakh S-class Haute Voiture limited edition will be listed together.

image001.jpg

[New Mercedes-Maibakh EQS pure electric SUV]

image002.jpg

[Mercedes-Maibakh S 580 e plug-in hybrid car]

image003.jpg

[Mercedes-Maibakh S-class Haute Voiture limited set]

  The EQG concept car, the first pure electric vehicle in the history of G-class off-road vehicle, will usher in the first show in China, and the EQG concept car will show its impressive strength by virtue of its powerful 4×4 all-wheel drive system with four independently controllable motors.

image004.jpg

  The new EQE pure electric SUV will usher in the first show in China. As the first domestic luxury pure electric SUV developed based on EVA pure electric platform, the new EQE pure electric SUV will set a market benchmark in terms of luxury, comfort, safety and technology with all-round strength, and bring all-powerful pure electric travel experience to China customers. In addition, a new generation of Mercedes-Benz GLE SUV will make its debut in China.

image005.jpg

[New EQE pure electric SUV]

image006.jpg

[New generation Mercedes-Benz GLE SUV]

  The new Mercedes-Benz long-wheelbase GLC SUV, which was pre-sold recently, will be officially launched at the auto show. As an important member of the domestic Mercedes-Benz family, the new long-wheelbase GLC SUV has added three rows and seven seats, making it the first model in the luxury medium-sized SUV market to offer both five-seat and seven-seat options, and at the same time, it has customized many exclusive upgrades for China customers.

  The S-class sedan family is about to welcome two new cars on the market: the Mercedes-Benz S 450 e L plug-in hybrid sedan equipped with the latest generation of plug-in hybrid technology, and the Mercedes-Benz S-class sedan that provides a variety of customized choices such as car paint and interior, which brings multiple respected choices for high-grade customers.

image007.jpg

[Mercedes-Benz S 450 e L]

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"Mercedes-Benz S-Class sedan ingenious version"

  At this auto show, Mercedes -AMG brought a number of latest masterpieces showing luxury performance and forward-looking innovation. The most powerful S-class sedan in history-the new Mercedes -AMG S 63 E PERFORMANCE prototype special edition will debut in China market. As the third production model of Mercedes -AMG family applying E PERFORMANCE hybrid technology from F1 racing car, this new work has achieved the perfect combination of excellent performance and comfortable experience with many forward-looking technologies.

image009.jpg

[Mercedes -AMG S 63 E PERFORMANCE pre-production special edition]

image010.jpg

[Mercedes -AMG GLS 63 4MATIC+]

image011.jpg

[New Mercedes -AMG pure electric EQE 53 4MATIC+]

image012.jpg

[Mercedes -AMG C 43 4MATIC Travel Car Special Edition]

  The newly launched Mercedes -AMG GLS 63 4MATIC+ will also make its debut in China. Mercedes -AMG’s second mass-produced pure electric vehicle, the brand-new Mercedes -AMG pure electric EQE 53 4MATIC+, and the brand-new Mercedes -AMG C 43 4MATIC touring car special edition equipped with "one person, one machine" M139 2.0T engine will be on the market, igniting driving passion with surging performance.

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All four teams won at home, and Real Madrid continued to follow Barcelona.

Last night and early this morning, there were four rematches in the 25th round of La Liga. The four home teams all scored points-Real Madrid beat the Spaniard 3-1 at home, while elche tied Balado Lide 1-1 at home; Certa beat Vallecano 3-0 at home, while Valencia beat Osasuna 1-0 in Mestalla and escaped from the relegation zone.

In terms of standings, Real Madrid shortened the gap with Barcelona to 6 points. Vallecano and Osasuna both lost and still ranked seventh and eighth; Valencia’s home win pushed Seville and almeria into the relegation zone, and the two teams will also have a direct dialogue in this round.

Real Madrid C.F.

Spanish

three

one

Real Madrid welcomes Spaniards at home. The Spaniard who fought away from home scored in the 8th minute, Ruben Sanchez crossed, and Jose Lu seized the opportunity to score 0-1. In 22 minutes, Venesius hit the right foot in the penalty area to equalize the score, 1-1. In 39 minutes, Chuameni assisted Militao to score a header, and 2-1, Real Madrid took the lead and entered the second half. In the 93rd minute, asensio, who came off the bench, received a pass from Na Qiao and scored another point. Real Madrid won 3-1 at home.

Elche

Real Valladolid Club de Fútbol

one

one

Elche, which ranks at the bottom, welcomes Balado Lide who has escaped from the relegation zone at home. Four minutes after the opening, Balado Lide was assisted by Olasa to score a goal by Lalin, 0-1. In 16 minutes, Plano hit the door slightly at a small angle. In 34 minutes, Boyer’s header missed. Elche trailed 0-1 in the first half. In 59 minutes, Boyer’s long-range shot was blocked. In 84 minutes, Raul Guti hit the door in the restricted area and was thrown. In 96 minutes, Morent volleyed and scored a tie, 1-1. Since then, Mesa and Hogela have been sent off for the second yellow card in this game. In the end, each side will get one point.

Certa Vigo

Vallecano

three

Zero

Certa, who played at home, took the initiative. In the 5 th minute, Bega’s long-range shot was saved. In 11 minutes, Lejon hit the door slightly higher outside the restricted area. In 41 minutes, aspas missed the goal from the left side of the penalty area. In the first half, the two sides drew a blank. In the 51st minute, Harvey Garland assisted aspas to score a goal from the left in the restricted area, 1-0. Then, carles Perez’s shot caused a Sis own goal, 2-0. In 85 minutes, aspas scored his second goal in this game, and Certa beat Vallecano 3-0.

Valencia

Osasuna

one

Zero

In the 6th minute, Diaca missed the header. In 11 minutes, Abd shot high. In 33 minutes, Hugo Duro shot in the restricted area and was saved. In the first half, the two sides drew a blank. Easy side fight again, 55 minutes, Avila shot high from the left side of the restricted area. In 74 minutes, Lino assisted Kluivert to score the only goal in the game, 1-0. In 89 minutes, Valencia got a penalty opportunity, and Hugo Duro was saved from the penalty, and the score remained unchanged. In the end, with the goal of Kluiwitt, the Bat Corps, which ranked second to last, won the game 1-0 and gained 3 valuable points.

Archsummit direct hit | Build a smooth natural flutter page

Instructors

Amoy Technology Department | Leisure Fish Technology | Cloud

"Fully strengthening the flutter fluidity, sharing challenges, online monitoring tool construction, optimization means to precipitate in component containers, and finally optimized advice."

Zhang Yunlong (cloud from), idle fish client experts.Since Netease, byte, Ali is running. At the current Department of Alibaba, there are currently responsible for idle fish APP packages, fluidity, start-up equation experience.

Outline

This sharing revolves around FLUTTER fluidity, respectively: 1.Flutter fluidity optimization challenge; 2. List container and flutterdx component optimization; 3. Performance measurement and devTool extension; 4.Fltter sliding curve optimization; 5. Performance optimization suggestions.

FLUTTER fluency optimization challenge

Business complexity challenge

FLUTTER has always been known by everyone, and the list controls displayed by Flutter Gallery (shown in the left) is indeed very smooth. But the actual business scene (shown on the right) is more complex than the Gallery list demo:

  1. Same card, more and complex (such as rounded) view control;

  2. When the list scroll, there are more view logic, such as scrolling control of other controls and disappearing;

  3. Card controls, there are more business logic, such as a different label, activity price, etc. based on background data, and there is also common business logic, etc.

  4. Because idle fish is an e-commerce app, we need to have certain dynamic capabilities to deal with frequently changed activities. Here we use the Flutter Dynamicx components of Ali to implement our dynamic capabilities.

Framework challenge

Let’s look at the overall flow of the list, here only pay attention to the free scroll phase after the finger is released.

  1. When the finger is released, the initial speed is calculated based on ScrollDragController.end;

  2. UI Thread requests RequestFrame to Platform Thread, and calls BegInframe to UI Thread at Platform Thread.

  3. The UI Thread Animate phase trigger list slides a little distance while registering the next frame callback to Platform Thread;

  4. Ui Thread Build Widget, generate / update the renderObject tree through the three tree DIFF algorithm of Flutter;

  5. UI Thread RenderObject Tree Layout, Paint Generates an Scene object, and finally passed to Raster Thread to draw on-screen;

The above flow must be completed in 16.6 ms to ensure that the frame cannot be guaranteed. Most of the cases, there is no need to build a new card, but when the new card enters the list area, the entire calculation amount will become huge, especially in complex business scenes, how to ensure all calculations within one frame of 16.6ms, Is a small challenge.

The figure above is a sliding devTool sample, and the Carton stage occurs when the new card is on the screen, and the other phases are very smooth, because the scrolling speed is attenuated, so the carton interval is also getting bigger. Because most of the time is very smooth, the average FPS is not low. However, the new card is built at the time of production, which gives us a stylish body feeling.

Challenge of dynamic capabilities – Flutter Dynamicx

The free fish APP card uses the self-developed Flutter Dynamicx to support our dynamic capabilities. Basic Principle: Online Edit Layout DSL, generate DX files and send it. The end side generates the DXComponentWidget by parsing the DX file and combines the back card data, and finally generates Widget Tree. FLUTTER DYNAMICX technology brings dynamic update capabilities, unified monitoring capabilities (such as dxcomponentwidget monitoring cards), good research and development insecurity (online DSL and Android Layout, and optimize Android), online editing capabilities;

But in performance, we also pay a certain price: DX cards add time to the template loading and data binding overhead, Widget wants to recursively create through WidgetNode traverses dynamically, and the view nesting layer will be deeper (followed by later).

Description: Flutter Dynamicx Reference Ali Group DSL Rules Realization

User’s sense of physical challenge

I have already described above, and the card in the FLUTTER list is more obvious.

When Android RecycleView occurs, the physical feel is not obvious, and the FLUTTER list has occurred when the card occurs, not only the time pause, but also a hopping on the OFFSET, and the physical feeling of small card is also changed. It is obvious;

Suppose the list content is simple enough, scrolling does not happen, we also found that the Flutter list and Android RecycleView are not the same:

? Use ClampingscrollPhysics to feel the feeling of similar magnets when the list is stopped.

? Use BOUNCINGSCROLLLPHYSICS, the list is started, and the speed attenuation is faster;

On the 90Hz machine, the early flutter list is not smooth, the reason is that the touch sampling rate is 120 Hz, and the screen refresh rate is 90Hz, causing partial screens to be 2 touch events, part is a 1 touch event, last Resulting in rolling OFFSET effects. When the Flutter 1.22 version, RESAMPLINGENABLED can be used to re-sample the touch event.

List container and flutterdx component optimization

Telling the challenge of Flutter fluidity optimization, now share how you optimize the smoothness and precipitate into PowerScrollView and Flutter Dynamic components.

PowerScrollView design and performance optimization

PowerscrollView is a snarefish team’s self-developing Flutter list assembly, with better packages and supplements on the Sliver Agreement: Data increased deletion, complement local refresh; layout, supplemented the waterfall flow; incident, supplement the card on the screen , Away, scrolling events; control, support for scrolling to Index.

In terms of performance, the waterfall flow layout optimization, local refresh optimization, card division optimization, and sliding curve optimization.

PowerScrollView Waterfall Flow Layout

PowerScrollView Waterfall Flow Layout provides longitudinal layout, lateral layout, mixed arrangement (transverse card and ordinary card mix). Nowadays, most of the listings of the hiped fish are available in PowerScrollView’s waterfall flow layout, such as the home page, search results page, etc.

PowerScrollView Waterfall Flow Layout Optimization

First, through conventional cache optimization, cache each card upper corner X value and which column belonging.

Compared to the Slivergrid card into the list area, the waterfall flow layout, we need to define Page, card admission to create and leave the field destruction need to be units. Before optimization, Page calculates cards in a screen visual area, and in order to determine the starting point Y value of Page, the primary layout needs to calculate the Page N and N + 1 two pages, so the amount of cards involved in the layout calculation is much lower, and the performance is low. After optimization, the approximation of all card height averages calculates Page, which greatly reduces the number of participating in the layout card, and the number of cards destroyed by Page also becomes less.

After the column cache and paging optimization, use the idle fish Self-developing Benchmark tool (follow-up) to compare the waterfall flow and GridView, view the number of frames and the worst frame consumption, can find that performance performance is basically consistent.

PowerScrollView local refresh optimization

Leisure fish products expect users to browse products more smooth, will not be loaded by loadmore, so the list is required to trigger LoadMore during scrolling. FLUTTER SLIVERLIST When the LOADMORE supplement card data, the List control is tender, and the slterlist building will destroy all cards and recreate it, and the performance data can be imagined very bad. PowerScrollView provides a layout refresh optimization: all cards on the cache screen, no longer recreate, ui thread Optimize from the original 34MS to 6MS (see the lower left picture), the right image is viewed by Timeline, the depth and complexity of the view built Optimize.

PowerScrollView card fragmentation optimization

The second figure 2 card is the early search results page of the idle fish, and it is not a waterfall flow. To view the Timeline chart when the card is created (adding DX Widget creation and PerformLayout overhead), you can find that the complexity of the card creation is extremely large. On the normal mid-range machine, the UI Thread consumes more than 30ms, to be optimized to 16.6ms It is very difficult to use routine optimization. For this purpose, two cards can be disassembled, and each frame is used to render.

Directly see the source code, the basic idea is to mark the card widget, when the card is true, the right card first _BuildPlaceHoldercell builds the Widget (empty Container), and register the next frame. In the next frame, the right card is modified with NeedShowRealcell for True, and self-laminate, and then build real content.

Is it delayed to build a true content of the card, will it affect the display content? Because the FLUTTER list has a cacheextends area on the visual area, this part of the area is not visible. In most scenarios, users don’t see the scene of the blank card.

Also using the FLUTTER BENCHMARK tool to perform performance test, you can see 90 points before and after the card division, 99 packet consumption has a significant downgrade, and the number of lost frames is also reduced from 39 to 27.

Note Here, when listening to the next frame, you need widgetsbinding.instance.scheduleframe to trigger the RequestFrame. Because when the list is displayed, it is possible because there is no callback from the next frame, resulting in the task of the delay display queue, eventually makes the first screen content display is incorrect.

Delayed framing optimization ideas and suggestions

Comparison of Flutter and H5 design:

  1. DART and JS are single-threaded models that need to be sequenced and deserialized across threads;

  2. Flutter Widget is similar to H5 VDOM, there is a DIFF process.

Early Facebook In React Optimization, the Fiber Architecture is proposed: Based on the VDOM Tree’s Parent Node → Sub-node → Brothers Node → Sub-node, the VDOM Tree is converted to the Fiber data structure (chain structure), and the reconcile phase is implemented. Interrupt recovery; based on the Fiber data structure, the control section continues in the next frame.

Based on React Fiber thinking, we propose its own delayed framing optimization, not just left and right card size, further, render content disassembled as the current frame task, high-excellent delay task and low delay tasks, the upper screen priority is sequentially changed Low. Where the current frame task is the left and right white Container; the high-optovel delay task is exclusively frame, where the picture portion also uses Container placeholders; in the idle fish scene, we dismantled all DX image widget from the card, as low as low Excellent delay tasks and is set to no more than 10 in one frame consumption.

By disassembling the 1 frame display task to 4 frames, the highest UI on the high-end machine will be optimized from 18 ms to 8 ms.

Description 1: Different business scenes, high-yogle and low-probing task settings have different description 2: Slide on the low-end machine (such as Vivo Y67), the sub-frame scheme will let the user see the list whitening and content Upable process

FLUTTER-DYNAMICX Component Optimization – Principle Explanation

Edit the "Class Android Layout DSL", compile the binary DX file. The end side is downloaded, loaded, and resolved, and the WidgetNode Tree is generated. See the right figure.

After the business data issued in the background, the Widget Tree is generated by recursively traversing WidgetNode Tree, and finally appears.

Description: Flutter Dynamicx Reference Ali Group DSL Rules Realization

FLUTTER-DYNAMICX Component Optimization – Cache Optimization

I know the principle, it is easy to discover the flow in the red box in the picture: binary (template) file parsing load, data binding, Widget dynamic creation has certain overhead. To avoid repeated overhead, we have cached DXWIDGETNODE and DXWIDGET, and the blue selection code shows the Widget cache.

FLUTTER-DYNAMICX Component Optimization – Independence ISOLATE Optimization

In addition, the above logic is placed in a stand-alone ISOLATE, and the maximum amount is lowered to the lowest. After the line technology grayscale AB experiment, the average carton bad frame ratio is reduced from 2.21% to 1.79%.

FLUTTER-DYNAMICX Component Optimization – Hierarchical Optimization

FLUTTER DYNAMICX provides class Android Layout DSL, adds Decoration layers to implement each control Padding, Margin, Corner, adds the Decoration layer; to implement the DXContainerRender layer. Every layer has its own clear duty, the code level is clear. However, since the increase in 2 layers caused the Widget Tree hierarchy, the DIFF logic of 3 trees became complicated and the performance becomes low. To do this, we merge the Decoration layer and the DXContainerRender layer, see the middle Timeline diagram, which can be found that the optimized flame grading and complexity becomes low. After the line technology grayscale AB experiment, the average carton bad frame ratio is reduced from 2.11% to 1.93%.

Performance measurement and devtool extension

Tell the optimization tool, which is described here to make a measure of how to measure, and the build / extension of the tool.

Offline scene – Flutter BenchmarkWhen the FLUTTER is detected, the calculation consumption on the UI Thread and Raster Thread is required. So the Flutter optimizes before and after comparison, using the time consuming data of the UI Thread and Raster Thread of each frame.

In addition, the fluency performance value is affected by the operating gesture, the scrolling speed, so the error based on the measurement results of manual operations will have errors. Here, use the WidgetController control list control FLING.

The tool provides the interval between the scrolling speed, the number of scrolls, the scroll, and the like. After the scrolling test is completed, the data is displayed by the UI and Raster Thread frame, 50 points, 90 points, and 99-positioned frame consumption, and give performance data from a variety of dimensions.

Offline scenario – Based on the recording screen

Flutter Benchmark gives multi-dimensional measurement data at the Flutter page, but sometimes we need a horizontal comparison competition app, so we need to have a tool transverse to more different technologies. The idle fish is self-developed in the Android side to self-developed the recording screen data. Imagine the mobile phone interface into multiple screens, get the screen data (byte arrays) (byte arrays) by sending VirtualDisplay, interval 16.6 ms, using the Hash value of the byte array represents the current picture, the current 2 The Hash-read hash value is unchanged, and the Carton is considered.

In order to ensure that the fluency detecting tool app itself does not have a carton, it is read, which is compressed, and the compression ratio on the low-end machine is higher.

Through the detection of the tool without invading, a rolling test can be detected, the average FPS value (57), the frame distribution is variance (7.28), 1S time, the large number of large cards (0.306), large card cumulative time (27.919). Intermediate array display frame distribution: 371 represents the number of normal frames, 6 generations 16.62ms of small cardon quantity, 1 generation 16.63MS quantity.

Here is the definition of the big Carton: Carton, greater than 16.6 * 2 ms.

Offline Scene – Performance Detection Based on DEVTOOL

In addition, the scenes of the idle fish are also extended DevTool. In a Timeline map extended time-consuming, greater than 16.6ms red highlight, convenient development.

Online scene-Flutter high available detection FPS implementation principle

Online scene, idle fish self-developed Flutter high available. The basic principle is based on 2 events:

  • Ui.window.onbeginframe event

    • Engine notifies the VYSNC signal arrival, notify UI Thread to start preparing the next frame building

    • Trigger schedulerbinding.handlebeginframe callback

  • Ui.window.ondrawframe event

    • Engine Notification UI Thread Start Draw Next Frame

    • Trigger schedulerbinding.handledrawframe callback

Here we have recorded a frame start event before the Handlebeginframe processing, and the end of the frame is recorded after HandledrawFrame. Each frame here needs to calculate the list control offset value, and the specific code implementation is implemented. When the entire accumulated exceeds 1, executes a calculation, filtering out the scene without scrolling, calculates the FPS value using each frame.

Online Scene – FlutterBlockcanary Line Stack Stack Detection

After using Flutter high available to get the online FPS value, how to locate the stack information, you need to collect stack information. Free fish collects carton stacks using the self-developed Flutterblockcanary. The basic principle is that the signal is transmitted in the C layer, such as 5ms once, each signal receives the Dart Ui Thread stack collection, the resulting series of stacks are aggregated, and the same stacks in a row are considered to have occurred in Carton, this This stack is the stack of Carton we want.

The following figure is the stack information collected by Flutterblockcanary, and the middle framefpsRecorder.getscrolloffset is a Carton call.

Online scene – FlutterBlockcanary Detects overreservation

In addition, FlutterBlockcanary also integrates over-rendering detection capabilities. Replace the Buildowner object by replying widgetsflutterbinding, replacing the buildowner object, and rewrive the ScheduleBuildFor method to intercept Element. Based on the dirty ELEMENT node, extract the depth of the dirty node, the number of direct child nodes, the number of all child nodes.

Based on the number of all child nodes, in the idle fish details page, we are positioned to the "Quick Question View" during scrolling, and the number of transes and all child nodes are too large. View the code, positioning the view hierarchical level, by sinking the view to the leaves node, the number of stasible Build nodes is optimized from 255 to 43.

FLUTTER sliding curve optimization

The front told Tarton optimization means and measures and standards are mainly surrounded by FPS. But from the user’s physical feel, we found that Flutter also has many optimal points.

FLUTTER list slide curve and native curve

Compare the scroll curve of OFFSET / TIME, you can find that the Flutter BouncingScrollsimulation and iOS scroll curve are close, Clampingscrollsimulation and RecyClerView are close. Check the Flutter source code, it is true.

Because BouncingScrollsimulation has rebound, many pull-down refreshes and load more features are based on BOUNCINGSCROLLSIMULATION package, which causes the Flutter page sliding, physical and native Android pages inconsistent.

Flutter list performance and optimization under fast sliding

Although the Clampingscrollsimulation slides and Android RecyclerView is close, but in the quick sliding scenario, you can find that the flutter list scrolls quickly stops, and quickly slides. For the reason, you can see the moment that the sliding curve is stopped, and the speed is not a decline, and it will speed up, finally reach the end point, and stop. Based on the source code formula, the curve can be discovered that flutter clampingscrollsimulation is approximated by the Formula Fitting Method to approximate the Android RecyclerView Curve. In the case of rapid sliding, the focus of the formula curve is not 1 corresponding value, but the right image is broken, the speed will become fast.

It can be understood that the FLUTTER’s formula fit is not ideal. In the near future, there is also a PR proposed using DART to implement the RecyclerView curve.

Flutter list performance and optimization in the case of Carton

The first chapter is mentioned in the case of the same FPS, such as the FPS 55, the native list feels smooth, and the styles of the FLUTTER list are more obvious. One reason here is that the native list usually has multiple thread operations, and there is a lower probability of the big Carton; the other reason is that the same small carton’s body, FLUTTER has obvious statter, and the native list can’t feel. So why?

When we build cards, we deliberately create small Carton, compare the flutter list and RecyclerView before and after, and you can find that RecyclerView Offset does not hop, and the Flutter curve has a lot of burrs, because Flutter scrolling is based on D / T curve calculation, When a carton occurs, △ t doubles, and OFFSET also trips. It is also because of time pause and offset jump, let users know that the Flutter list is not unstoppable in small Carton.

By modifying the Y=D (T) formula, in the case of Carton, ΔT-16.6ms will ensure that the small Carton case is not hopped. In the case of Great Carton, it is not necessary to reset the ΔT to 16.6ms, because in the parking time, it has been clearly allowed to give the user to feel the carton, OFFSET does not have a trip only to make the list rolling distance short.

Performance optimization

Finally share some suggestions for performance optimization.

  1. In optimization, we should pay more attention to the user’s body, not only the performance value. The upper right map is visible, even if the FPS value is the same, but the taste occurs, the body feels clearly; the bottom of 2 game recording screens, the left side average 40 fps, the average of 30 fps, but the body feels is more smooth .

  2. Not only should I pay attention to the performance of UI Thread, but also pay attention to the overhead of Raster Thread, such as the characteristics / operation of Save Layer, but also causing Carton.

  3. In terms of tool, it is recommended to use different tools in different scenarios. It should be noted that the problem of tool detection is a stable reproduction problem or the occasion of data jitter. In addition, it is also necessary to consider the performance overhead of the tool itself, and the tool itself needs to be as low as possible.

  4. In terms of optimization ideas, we must broaden the direction. Most optimized ideas of Flutter are optimized computing tasks; and multithreading direction is not, refer to the independent ISOLATE Optimization of Flutter Dynamicx; in addition, it is difficult to digestive tasks for one frame Whether it is possible to disassemble multiple frame time, try to make a card per frame, priority to the user.

  5. Finally, I recommend paying attention to the Flutter community. The Flutter community continues to have a variety of optimization, regularly upgraded Flutter or dimensions, CHERRY-PICK optimization submission, is a good choice.

Performance analysis tool usage suggestions

Flutter tool, the first push is the official devtools tool, the Timeline and CPU Flammatic maps can help us discover problems well; in addition, Flutter also provides a wealth of Debug Flags to assist our positioning problems, familiar with each Debug switch Role, I believe that there will be no homage to our daily research and development; in addition to official tools, performance logs are also good auxiliary information, as shown in the lower right corner, the idle fish Fish-Redux component outputs the task overhead in the scroll, can It is convenient to see that at that moment.

Performance analysis tools themselves

Performance testing tools inevitably have certain overhead, but must be controlled within an acceptable range, especially on the line. A case in front sharing the FLUTTERBLOCKCANARY detection tool, discovers the framefpsRecorder.getscrolloffset time consumption, and the logic is just that Flutter is highly available to scroll offset. See the right front source code of the right picture, each frame needs to be recursively traversed to collect RenderViewPortBase, which is a small overhead. Finally, we avoid the repetition calculations during the scroll through the cache optimization.

Carton optimization suggestions

Reference official documents and excellent performance articles, precipitated a lot of routine optimization methods in the UI and GPU side, such as refreshing the minimum widget, using itemextent, recommended using Selector and Consumer, etc., avoid unnecessary DIFF computing, layout calculation, etc. Reduce SAVELAYER, replace half-transparent effects using images, alleviate the overhead of the Raster thread.

Because of the reasons, only part of the sequence, more common optimization suggestions see the official documentation.

Use the latest Flutter Engine

As mentioned earlier, the Flutter community is also active, Framework and Engine layers have an optimized PR income, which mostly can make the business layer without perception, and better optimize performance from the bottom viewing angle.

Here, there is a typical optimization scheme: existing flutter solution: When each VSYNC signal arrives, it triggers the build operation. At the end of Build, start register the next vsync callback. In the case where a carton does not occur, see Figure Normal. However, in the case of carton, see Figure Actual Results, just over 16.6ms here, because it is a registration listening to the next vsync callback, triggered the next build, for this, a large amount of time in the middle. Obviously, what we expect is, at the end, immediately execute, assuming enough to execute enough, this time the screen is still smooth.

If the team allows, it is recommended to upgrade the flutter version regularly; or maintain your own Flutter independent branch is also a good choice. From the community Cherry-Pick optimization, you can guarantee that business stability can also enjoy the community contribution. In short, I recommend you to pay attention to the community.

Summarize

In summary, the challenges, monitoring tools, optimization methods, and recommendations are shared by Flutter fluidity optimization. Performance optimization should be people-centered, develop monitoring indicators and optimization points from actual physical fitness; fluency optimization is not one, the above share is not all, there are many optimized means to pay attention: How to better multiplex Element, how to avoid Platform Thread busy leading to vsync signal lacking, etc., is a point that can be concerned. Only the continuous technical enthusiasm and conscious spirit can optimize the APP performance to the ultimate; technical teams also have access to open source communities, other teams / companies to connect, That stone stone, Can be attacked.