我正在尝试在窗户的背景上绘制一些东西。因此,我将窗口的NSView子类化,并添加了一些类似的绘图代码:
- (void)drawRect:(NSRect)dirtyRect {
float color = 0.95;
[[NSColor colorWithDeviceRed:color green:color blue:color alpha:1.0] set];
NSRectFill(NSMakeRect(320, 0, 220, NSHeight(dirtyRect)-60));
}
这很好用,但是只要我打开一个NSComboBox或者我激活了一个复选框,这些元素的背景就会删除我刚绘制的矩形。
我不明白这一点,因为检查例如复选框导致,调用drawRect(我添加了一个NSLog)。只调整窗口大小再次绘制我的矩形。
编辑: 这是问题的截图:
答案 0 :(得分:2)
我有时会遇到同样的问题。我认为以下是我的用法。
/// .h
@interface BackgroundView1 : NSView {
NSImage *myImage;
}
// .m
- (void)awakeFromNib {
[self setupBackgroundImage];
}
- (void)setupBackgroundImage {
NSColor *c = [NSColor colorWithDeviceRed:0.0f/255.0f green:55.0f/255.0f blue:150.0f/255.0f alpha:1.0f];
if (myImage == nil)
myImage = [self createColorImage:NSMakeSize(1,1):c];
}
- (void)drawRect:(NSRect)rect {
[myImage drawInRect:NSMakeRect([self bounds].origin.x,[self bounds].origin.y,[self frame].size.width,[self frame].size.height)
fromRect:NSMakeRect(0,0,[myImage size].width, [myImage size].height)
operation:NSCompositeCopy
fraction:1.0];
}
// Start Functions //
- (NSImage *)createColorImage:(NSSize)size :(NSColor *)color {
NSImage *image = [[NSImage alloc] initWithSize:size];
NSBitmapImageRep *rep = [[NSBitmapImageRep alloc]
initWithBitmapDataPlanes:NULL
pixelsWide:size.width
pixelsHigh:size.height
bitsPerSample:8
samplesPerPixel:4
hasAlpha:YES
isPlanar:NO
colorSpaceName:NSCalibratedRGBColorSpace
bytesPerRow:0
bitsPerPixel:0];
[image addRepresentation:rep];
[image lockFocus]; // Lock focus of image, making it a destination for drawing
[color set];
NSRectFill(NSMakeRect(0,0,size.width,size.height));
[image unlockFocus];
return image;
}
// End Functions //