Report correct refresh rate if updated in a new frame #30054
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cyanglaz
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Please rebase this change to fix the windows UWP build |
| display_manager_->UpdateRefreshRateIfNecessary( | ||
| flutter::DisplayUpdateType::kUpdateRefreshRate, vsync_start_time, | ||
| frame_target_time); |
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What's the cost of this on iOS? We know for sure that on some Android platforms it's pretty expensive (e.g. 2-5ms) and this is during frameworkload.
Can we instead listen to refresh rate updates from the OS somehow?
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Could you elaborate how this is expensive on Android. This method is essentially a no-op if framerate doesn't change. See: https://github.com/flutter/engine/pull/30054/files#diff-c9141b5122b7cb9dcc29a05b1660dbb92c1c6ea8e0df831c96b42708fa1e20b5R66
(I should probably need to update the code to return early so it is clearer)
shell/common/display_manager.cc
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| double new_frame_rate = | ||
| round((1 / (frame_target_time - vsync_start_time).ToSecondsF())); | ||
| if (!is_frame_rate_same(GetMainDisplayRefreshRate(), new_frame_rate)) { |
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On Android now this should always return false, but I'm curious if iOS can do something closer to what Android does and just supply a display object that always returns the right value for GetMainDisplayRefreshRate rather than polling/checking every frame.
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On iOS, we can only get the frame time from target_time - start_time. We can have a platform(iOS) layer object to manage that calculation so it is abstracted from other platforms.
I think it is true for all the platforms that target_time - start_time represents the frame duration, and doing such calculation per frame is not expensive?
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How do you calculate the target_time on iOS?
On Android, it's calculated using the frame rate - requesting the frame rate every frame is expensive on Android in some vendor implementations though.
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Close in favor of #30223 |
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This PR makes the DisplayManager determines the frame rate at the beginning of each frame and update the reporting accordingly.
Fixes flutter/flutter#94507
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