透明繪制圖像

Question

我有一些png，它們彼此疊加以在beginGraphicsContextWithOptions中形成單個圖像。...但是，我想以透明性繪制其中的某些圖像。 我該怎么做？

Answer 1

這是使用透明圖像疊加圖像的方法：

NSString* file1 = "your images file path";

NSRect largerect = NSRectMake(10,10,300,300);

NSString* file2 = "your images file path";

NSString* file3 = "your images file path";

NSString* file4 = "your images file path";

NSImage* img1 = [[NSImage alloc] initWithContentsOfFile:file1];

NSImage* img2 = [[NSImage alloc] initWithContentsOfFile:file1];

NSImage* img3 = [[NSImage alloc] initWithContentsOfFile:file1];

NSImage* img4 = [[NSImage alloc] initWithContentsOfFile:file1];

//the fraction parameter is just how transparent you want it so 1.0 is opaque and 0.0      you will not see the image

[image1 drawInRect: largeRect
      fromRect: NSZeroRect
     operation: NSCompositeSourceOver
      fraction: 0.8];

[image2 drawInRect: largeRect
      fromRect: NSZeroRect
     operation: NSCompositeSourceOver
      fraction: 0.6];

[image1 drawInRect: smallRect1
      fromRect: NSZeroRect
     operation: NSCompositeSourceOver
      fraction: 0.40];

[image2 drawInRect: smallRect2
      fromRect: NSZeroRect
     operation: NSCompositeSourceOver
      fraction: 0.40];