GPUImage源码解读(八)

从名称就可以知道GPUImageView是GPUImage框架中显示图片相关的类。GPUImageView实现了GPUImageInput协议,从而可以知道它能够接受GPUImageFramebuffer的输入。因此,常常作为响应链的终端节点,用于显示处理后的帧缓存。

- 重写静态方法 返回 CAEAGLLayer

GPUImageView 是UIView的子类,所以会有UIView所有方法特性。UIView也可以使用不同的CALayer来显示,添加OpenGL ES实现View绘制的使用

- (Class)layerClass
{
return [CAEAGLLayer class];
}

初始化 方法

最后都会调用 commonInit 方法

- (id)initWithFrame:(CGRect)frame;
- (id)initWithCoder:(NSCoder *)coder;

实现方法

- (void)commonInit;
{
// Set scaling to account for Retina display
if ([self respondsToSelector:@selector(setContentScaleFactor:)])
{
self.contentScaleFactor = [[UIScreen mainScreen] scale];
}
inputRotation = kGPUImageNoRotation;
self.opaque = YES;
self.hidden = NO;
//1,设置OpenGL ES的相关属性
CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer;
eaglLayer.opaque = YES;
eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:NO], kEAGLDrawablePropertyRetainedBacking, kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil];
self.enabled = YES;
runSynchronouslyOnVideoProcessingQueue(^{
[GPUImageContext useImageProcessingContext];
//2、创建着色器程序;
displayProgram = [[GPUImageContext sharedImageProcessingContext] programForVertexShaderString:kGPUImageVertexShaderString fragmentShaderString:kGPUImagePassthroughFragmentShaderString];
if (!displayProgram.initialized)
{
//3、获取属性变量、统一变量的位置
[displayProgram addAttribute:@"position"];
[displayProgram addAttribute:@"inputTextureCoordinate"];
if (![displayProgram link])
{
NSString *progLog = [displayProgram programLog];
NSLog(@"Program link log: %@", progLog);
NSString *fragLog = [displayProgram fragmentShaderLog];
NSLog(@"Fragment shader compile log: %@", fragLog);
NSString *vertLog = [displayProgram vertexShaderLog];
NSLog(@"Vertex shader compile log: %@", vertLog);
displayProgram = nil;
NSAssert(NO, @"Filter shader link failed");
}
}
displayPositionAttribute = [displayProgram attributeIndex:@"position"];
displayTextureCoordinateAttribute = [displayProgram attributeIndex:@"inputTextureCoordinate"];
displayInputTextureUniform = [displayProgram uniformIndex:@"inputImageTexture"]; // This does assume a name of "inputTexture" for the fragment shader
[GPUImageContext setActiveShaderProgram:displayProgram];
glEnableVertexAttribArray(displayPositionAttribute);
glEnableVertexAttribArray(displayTextureCoordinateAttribute);
//4、设置清屏颜色
[self setBackgroundColorRed:0.0 green:0.0 blue:0.0 alpha:1.0];
_fillMode = kGPUImageFillModePreserveAspectRatio;
//5、创建默认的帧缓存、渲染缓存,用于图像的显示
[self createDisplayFramebuffer];
});
}

方法列表

// 设置背景颜色
- (void)setBackgroundColorRed:(GLfloat)redComponent green:(GLfloat)greenComponent blue:(GLfloat)blueComponent alpha:(GLfloat)alphaComponent;
// 该方法未实现
(void)setCurrentlyReceivingMonochromeInput:(BOOL)newValue;

实现方法

// 根据旋转模式获取纹理坐标
- (const GLfloat *)textureCoordinatesForRotation:(GPUImageRotationMode)rotationMode;
{
// static const GLfloat noRotationTextureCoordinates[] = {
// 0.0f, 0.0f,
// 1.0f, 0.0f,
// 0.0f, 1.0f,
// 1.0f, 1.0f,
// };
static const GLfloat noRotationTextureCoordinates[] = {
0.0f, 1.0f,
1.0f, 1.0f,
0.0f, 0.0f,
1.0f, 0.0f,
};
static const GLfloat rotateRightTextureCoordinates[] = {
1.0f, 1.0f,
1.0f, 0.0f,
0.0f, 1.0f,
0.0f, 0.0f,
};
static const GLfloat rotateLeftTextureCoordinates[] = {
0.0f, 0.0f,
0.0f, 1.0f,
1.0f, 0.0f,
1.0f, 1.0f,
};
static const GLfloat verticalFlipTextureCoordinates[] = {
0.0f, 0.0f,
1.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
};
static const GLfloat horizontalFlipTextureCoordinates[] = {
1.0f, 1.0f,
0.0f, 1.0f,
1.0f, 0.0f,
0.0f, 0.0f,
};
static const GLfloat rotateRightVerticalFlipTextureCoordinates[] = {
1.0f, 0.0f,
1.0f, 1.0f,
0.0f, 0.0f,
0.0f, 1.0f,
};
static const GLfloat rotateRightHorizontalFlipTextureCoordinates[] = {
1.0f, 1.0f,
1.0f, 0.0f,
0.0f, 1.0f,
0.0f, 0.0f,
};
static const GLfloat rotate180TextureCoordinates[] = {
1.0f, 0.0f,
0.0f, 0.0f,
1.0f, 1.0f,
0.0f, 1.0f,
};
switch(rotationMode)
{
case kGPUImageNoRotation: return noRotationTextureCoordinates;
case kGPUImageRotateLeft: return rotateLeftTextureCoordinates;
case kGPUImageRotateRight: return rotateRightTextureCoordinates;
case kGPUImageFlipVertical: return verticalFlipTextureCoordinates;
case kGPUImageFlipHorizonal: return horizontalFlipTextureCoordinates;
case kGPUImageRotateRightFlipVertical: return rotateRightVerticalFlipTextureCoordinates;
case kGPUImageRotateRightFlipHorizontal: return rotateRightHorizontalFlipTextureCoordinates;
case kGPUImageRotate180: return rotate180TextureCoordinates;
}
}
// 覆盖父类的方法,作用是负责OpenGL的图形绘制,并显示在屏幕上
- (void)newFrameReadyAtTime:(CMTime)frameTime atIndex:(NSInteger)textureIndex;
{
runSynchronouslyOnVideoProcessingQueue(^{
[GPUImageContext setActiveShaderProgram:displayProgram];
[self setDisplayFramebuffer];
// 清屏
glClearColor(backgroundColorRed, backgroundColorGreen, backgroundColorBlue, backgroundColorAlpha);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glActiveTexture(GL_TEXTURE4);
glBindTexture(GL_TEXTURE_2D, [inputFramebufferForDisplay texture]);
glUniform1i(displayInputTextureUniform, 4);
glVertexAttribPointer(displayPositionAttribute, 2, GL_FLOAT, 0, 0, imageVertices);
glVertexAttribPointer(displayTextureCoordinateAttribute, 2, GL_FLOAT, 0, 0, [GPUImageView textureCoordinatesForRotation:inputRotation]);
// 绘制
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
// 显示
[self presentFramebuffer];
[inputFramebufferForDisplay unlock];
inputFramebufferForDisplay = nil;
});
}
// 显示帧缓存
- (void)presentFramebuffer;
{
glBindRenderbuffer(GL_RENDERBUFFER, displayRenderbuffer);
[[GPUImageContext sharedImageProcessingContext] presentBufferForDisplay];
}