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

实现方法

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