【CoreGraphics】CGGradient - 渐变 组件

用于 CGContext 绘制渐变使用

typedef CF_OPTIONS (uint32_t, CGGradientDrawingOptions) {
  kCGGradientDrawsBeforeStartLocation = (1 << 0),
  kCGGradientDrawsAfterEndLocation = (1 << 1)
};// 渐变选项

• 颜色组件 梯度初始化

    CGColorSpaceRef spaceRef = CGColorSpaceCreateDeviceRGB();
    CGFloat components[] = {1,0,0,1, 0,1,0,1, 0,0,1,1};
    CGFloat locations[] = {0.0, 0.5, 1.0};
    CGGradientRef gradeRef = CGGradientCreateWithColorComponents(spaceRef,
                                                                 components,
                                                                 locations,
                                                                 sizeof(locations)/sizeof(locations[0]));
    

• 颜色数组 梯度初始化

    CGColorSpaceRef spaceRef = CGColorSpaceCreateDeviceRGB();

     CGFloat locations[] = {0.0, 0.5, 1.0};
 
    // 创建 颜色1
    CGFloat beginColor[] = {1,0,0,1};
    CGColorRef beginColorRef = CGColorCreate(spaceRef, beginColor);
    
    // 创建 颜色2
    CGFloat midColor[] = {0,1,0,1};
    CGColorRef midColorRef = CGColorCreate(spaceRef, midColor);
    
    // 创建 颜色3
    CGFloat endColor[] = {0,0,1,1};
    CGColorRef endColorRef = CGColorCreate(spaceRef, endColor);
    
    // 创建颜色数组
    CFArrayRef colorArrayRef = CFArrayCreate(kCFAllocatorDefault,
                                             (const void*[]){beginColorRef, midColorRef,endColorRef},
                                             3,
                                             nil);
    
    // 渐变
    CGGradientRef gradeRef2 =  CGGradientCreateWithColors(spaceRef,
                                                            colorArrayRef,
                                                            locations);

操作

CG_EXTERN CGGradientRef __nullable CGGradientRetain(
    CGGradientRef __nullable gradient)
    CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

 
CG_EXTERN void CGGradientRelease(CGGradientRef __nullable gradient)
    CG_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);

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