drawrect

I followed a tutorial online to draw in a subclassed UIView. The tutorial showed a UIView with a white background, I fixed this by simply changing the super's bg color. The problem is, when touches end, the background does not remain clear. I have no idea. I simply tried setting the fill color to [uicolor clearcolor]; unsuccessfully. Here is the code I am using: @implementation CachedLIView { UIBezierPath *path; UIImage *incrementalImage; // (1) } - (id)initWithCoder:(NSCoder *)aDecoder { if (self = [super initWithCoder:aDecoder]) { [self setMultipleTouchEnabled:NO]; [self setBackgroundColor:

I want to paint the background of a slider. I tried this but the color covers up the whole slider. This is in an inherited class of QSlider void paintEvent(QPaintEvent *e) { QPainter painter(this); painter.begin(this); painter.setBrush(/*not important*/); // This covers up the control. How do I make it so the color is in // the background and the control is still visible? painter.drawRect(rect()); painter.end(); } To set the background of a widget you could set the style sheet: theSlider->setStyleSheet("QSlider { background-color: green; }"); The following will set the background of the widget

In my drawRect method, I am drawing a PNG image. On top of that, I want to draw a rect with a 20% alpha color, like this: [[UIColor colorWithWhite:0.0 alpha:0.2] set]; UIRectFill(rect); The problem is, that the alpha property seems to get ignored. No alpha is applied at all, just a black rectangle is drawn. How can I fix this? Thanks in advance! Use CGContextSetBlendMode() before you draw the rect. Set your view background color to transparent… It should work. 来源： https://stackoverflow.com/questions/2935608/how-can-i-fill-a-rect-with-an-alpha-color-using-coregraphics

I'm using a custom UITableViewCell , into which I am placing a subclassed UIView (within contentView , natch). The UIView in question displays a directional arrow and two lines of supporting text. The arrow is displayed by means of a layer with a background color and an arrow-shaped mask. The background color changes to one of two possibilities depending on the direction the arrow is pointing. The view receives a NSNotification whenever it needs to update the arrow (based on, but not identical to, the current heading - each cell and view is different). When it receives notice, the view calls a

I am trying to override the drawRect: method of UIView in my custom view. However, my view has a border radius defined as: sub = [[[NSBundle mainBundle] loadNibNamed:@"ProfileView" owner:self options:nil] objectAtIndex:0]; [self addSubview:sub]; [sub setUserInteractionEnabled:YES]; [self setUserInteractionEnabled:YES]; CALayer *layer = sub.layer; layer.masksToBounds = YES; layer.borderWidth = 5.0; layer.borderColor = [UIColor whiteColor].CGColor; layer.cornerRadius = 30.0; This works perfectly and places a nice border with a border radius around my view (don't mind the diagonal/straight white