我有油漆应用程序。当我单击按钮时,它会启动绘画视图,而不是用户可以绘画。在我回来然后单击按钮后,paintview 将不会重置。绘制疼痛后如何在按钮单击中重置视图。
代码:
- (BOOL) initContext:(CGSize)size {
int bitmapByteCount;
int bitmapBytesPerRow;
// Declare the number of bytes per row. Each pixel in the bitmap in this
// example is represented by 4 bytes; 8 bits each of red, green, blue, and
// alpha.
bitmapBytesPerRow = (size.width * 4);
bitmapByteCount = (bitmapBytesPerRow * size.height);
// Allocate memory for image data. This is the destination in memory
// where any drawing to the bitmap context will be rendered.
cacheBitmap = malloc( bitmapByteCount );
if (cacheBitmap == NULL){
return NO;
}
cacheContext = CGBitmapContextCreate (cacheBitmap, size.width, size.height, 8, bitmapBytesPerRow, CGColorSpaceCreateDeviceRGB(), kCGImageAlphaNoneSkipFirst);
return YES;
}
- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
[self drawToCache:touch];
[self setNeedsDisplay];
}
- (void) drawToCache:(UITouch*)touch {
hue += 0.005;
if(hue > 1.0) hue = 0.0;
UIColor *color = [UIColor colorWithHue:hue saturation:0.7 brightness:1.0 alpha:1.0];
CGContextSetStrokeColorWithColor(cacheContext, [color CGColor]);
CGContextSetLineCap(cacheContext, kCGLineCapRound);
CGContextSetLineWidth(cacheContext, 15);
CGPoint lastPoint = [touch previousLocationInView:self];
CGPoint newPoint = [touch locationInView:self];
CGContextMoveToPoint(cacheContext, lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(cacheContext, newPoint.x, newPoint.y);
CGContextStrokePath(cacheContext);
CGRect dirtyPoint1 = CGRectMake(lastPoint.x-10, lastPoint.y-10, 20, 20);
CGRect dirtyPoint2 = CGRectMake(newPoint.x-10, newPoint.y-10, 20, 20);
[self setNeedsDisplayInRect:CGRectUnion(dirtyPoint1, dirtyPoint2)];
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
CGContextRef context = UIGraphicsGetCurrentContext();
CGImageRef cacheImage = CGBitmapContextCreateImage(cacheContext);
CGContextDrawImage(context, self.bounds, cacheImage);
CGImageRelease(cacheImage);
}
在视图控制器代码中:
PaintView *paint = [[PaintView alloc] initWithFrame:self.view.bounds];
[self.view addSubview:paint];
[paint release];