webrtc视频渲染经常调整渲染方式，看看webrtc下怎么做：
- 保持比例裁剪填充(SCALE_ASPECT_FILL，适合人头画面)，
- 保持比例显示全部画面(SCALE_ASPECT_FIT，适合屏幕共享)
由用户调整RTCVideoRenderer在父视图中的显示区域bounds完成。
- opengl或者Metal的接口RTCVideoRenderer.h都回调视频的高宽变化 ``` //RTCVideoRenderer.h
- (void)videoView:(RTC_OBJC_TYPE(RTCNSGLVideoView) *)videoView didChangeVideoSize:(NSSize)size ```
- 用户更加变化自己调整视频显示 ``` //ARDVideoCallView.m
- (void)videoView:(id<RTC_OBJC_TYPE(RTCVideoRenderer)>)videoView didChangeVideoSize:(CGSize)size { if (videoView == _remoteVideoView) { _remoteVideoSize = size; } [self setNeedsLayout]; } ```
- 调整方法 ```
- (void)layoutSubviews { CGRect bounds = self.bounds; if (_remoteVideoSize.width > 0 && _remoteVideoSize.height > 0) { // Aspect fill remote video into bounds. CGRect remoteVideoFrame = AVMakeRectWithAspectRatioInsideRect(_remoteVideoSize, bounds); CGFloat scale = 1; if (remoteVideoFrame.size.width > remoteVideoFrame.size.height) { // Scale by height. scale = bounds.size.height / remoteVideoFrame.size.height; } else { // Scale by width. scale = bounds.size.width / remoteVideoFrame.size.width; } remoteVideoFrame.size.height *= scale; remoteVideoFrame.size.width *= scale; _remoteVideoView.frame = remoteVideoFrame; _remoteVideoView.center = CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds)); } else { _remoteVideoView.frame = bounds; }
….. }
### 二. android的SurfaceViewRenderer
> - 通过onMeasure调整view的实现
> - 可以根据父容器自动调整view的大小，不用sdk用户在重新计算
> - 所以SurfaceViewRenderer要放到一个更大的父容器里面且高宽是wrap_content，才能实现保持比例显示全部画面SCALE_ASPECT_FIT
- SurfaceViewRenderer.java缩放控制参数
renderer.setScalingType(RendererCommon.ScalingType.SCALE_ASPECT_FIT,RendererCommon.ScalingType.SCALE_ASPECT_FIT); ```
RendererCommon.java核心类，用于控制和计算renderview的高宽 ``` public void setScalingType( ScalingType scalingTypeMatchOrientation, ScalingType scalingTypeMismatchOrientation) { this.visibleFractionMatchOrientation = convertScalingTypeToVisibleFraction(scalingTypeMatchOrientation); this.visibleFractionMismatchOrientation = convertScalingTypeToVisibleFraction(scalingTypeMismatchOrientation); }
private static float convertScalingTypeToVisibleFraction(ScalingType scalingType) { switch (scalingType) { case SCALE_ASPECT_FIT: return 1.0f; case SCALE_ASPECT_FILL: return 0.0f; case SCALE_ASPECT_BALANCED: return BALANCED_VISIBLE_FRACTION; default: throw new IllegalArgumentException(); }
public static Point getDisplaySize( float minVisibleFraction, float videoAspectRatio, int maxDisplayWidth, int maxDisplayHeight) { // If there is no constraint on the amount of cropping, fill the allowed display area. if (minVisibleFraction == 0 || videoAspectRatio == 0) { return new Point(maxDisplayWidth, maxDisplayHeight); } // Each dimension is constrained on max display size and how much we are allowed to crop. final int width = Math.min( maxDisplayWidth, Math.round(maxDisplayHeight / minVisibleFraction * videoAspectRatio)); final int height = Math.min( maxDisplayHeight, Math.round(maxDisplayWidth / minVisibleFraction / videoAspectRatio)); return new Point(width, height); }
//videoLayoutMeasure.measure public Point measure(int widthSpec, int heightSpec, int frameWidth, int frameHeight) { // Calculate max allowed layout size. final int maxWidth = View.getDefaultSize(Integer.MAX_VALUE, widthSpec); final int maxHeight = View.getDefaultSize(Integer.MAX_VALUE, heightSpec); if (frameWidth == 0 || frameHeight == 0 || maxWidth == 0 || maxHeight == 0) { return new Point(maxWidth, maxHeight); } // Calculate desired display size based on scaling type, video aspect ratio, // and maximum layout size. final float frameAspect = frameWidth / (float) frameHeight; final float displayAspect = maxWidth / (float) maxHeight; final float visibleFraction = (frameAspect > 1.0f) == (displayAspect > 1.0f) ? visibleFractionMatchOrientation : visibleFractionMismatchOrientation; final Point layoutSize = getDisplaySize(visibleFraction, frameAspect, maxWidth, maxHeight);
// If the measure specification is forcing a specific size - yield.
if (View.MeasureSpec.getMode(widthSpec) == View.MeasureSpec.EXACTLY) {
layoutSize.x = maxWidth;
}
if (View.MeasureSpec.getMode(heightSpec) == View.MeasureSpec.EXACTLY) {
layoutSize.y = maxHeight;
}
return layoutSize;
} ```
SurfaceViewRenderer.java在onMeasure计算自己的高宽，updateSurfaceSize更新显示区域 ``` // View layout interface. @Override protected void onMeasure(int widthSpec, int heightSpec) { ThreadUtils.checkIsOnMainThread(); Point size = videoLayoutMeasure.measure(widthSpec, heightSpec, rotatedFrameWidth, rotatedFrameHeight); setMeasuredDimension(size.x, size.y); logD(“onMeasure(). New size: “ + size.x + “x” + size.y); }
@Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { ThreadUtils.checkIsOnMainThread(); eglRenderer.setLayoutAspectRatio((right - left) / (float) (bottom - top)); updateSurfaceSize(); }
private void updateSurfaceSize() { ThreadUtils.checkIsOnMainThread(); if (enableFixedSize && rotatedFrameWidth != 0 && rotatedFrameHeight != 0 && getWidth() != 0 && getHeight() != 0) { final float layoutAspectRatio = getWidth() / (float) getHeight(); final float frameAspectRatio = rotatedFrameWidth / (float) rotatedFrameHeight; final int drawnFrameWidth; final int drawnFrameHeight; if (frameAspectRatio > layoutAspectRatio) { drawnFrameWidth = (int) (rotatedFrameHeight * layoutAspectRatio); drawnFrameHeight = rotatedFrameHeight; } else { drawnFrameWidth = rotatedFrameWidth; drawnFrameHeight = (int) (rotatedFrameWidth / layoutAspectRatio); } // Aspect ratio of the drawn frame and the view is the same. final int width = Math.min(getWidth(), drawnFrameWidth); final int height = Math.min(getHeight(), drawnFrameHeight); logD(“updateSurfaceSize. Layout size: “ + getWidth() + “x” + getHeight() + “, frame size: “ + rotatedFrameWidth + “x” + rotatedFrameHeight + “, requested surface size: “ + width + “x” + height + “, old surface size: “ + surfaceWidth + “x” + surfaceHeight); if (width != surfaceWidth || height != surfaceHeight) { surfaceWidth = width; surfaceHeight = height; getHolder().setFixedSize(width, height); } } else { surfaceWidth = surfaceHeight = 0; getHolder().setSizeFromLayout(); } } ```