标签: drawrect

致电所有专家!我见过各种帖子,说实话,我的需求与SO上的答案略有不同.

我想创建一个UI,用户可以在特定区域创建各种线条(直线,曲线,摆动等)(现在我们称之为"画布").每行可以有多个实例.然后,用户可以根据需要拖动和编辑这些行.因此,他们可以拉伸它,更改起点,终点等,甚至可以将整行拖动到画布的边界内.

我设法画线(使用drawRect)并在每一行的末尾显示可拖动的手柄(参见参考图像),用户可以在画布的边界(红色矩形)内拖动端点以满足需要.

我面临的问题是如何点击以激活特定行的编辑.因此,默认情况下,拖动句柄将不可见,并且用户可以点击该行以激活"编辑"模式,然后显示句柄(再次点按以取消选择).因此,在上图中,我希望能够检测黄色矩形中的触摸.请记住,UIView边界是整个画布区域,允许用户自由拖动,因此检测触摸显然很困难,因为还有透明区域,并且每行可以有多个实例.

这是我的代码到目前为止的行类(startHandle和endHandle是每一端的句柄):

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    CGPoint startPoint = CGPointMake(self.startHandle.frame.origin.x + self.startHandle.frame.size.width/2, self.startHandle.frame.origin.y + self.startHandle.frame.size.height/2);

    CGPoint endPoint = CGPointMake(self.endHandle.frame.origin.x + self.endHandle.frame.size.width/2, self.endHandle.frame.origin.y + self.endHandle.frame.size.height/2);

    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchLocation = [touch locationInView:self];

    if (CGRectContainsPoint(CGRectMake(startPoint.x, startPoint.y, endPoint.x - startPoint.x , endPoint.y - startPoint.y), touchLocation))
    {
        //this is the green rectangle! I want the yellow one :)
        NSLog(@"TOUCHED IN HIT AREA");
    }
}

- (void)drawRect:(CGRect)rect {
    [super drawRect:rect];

    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextClearRect(context, …

我做了一个光滑的NSScroller子类,但无法弄清楚如何使它覆盖在顶部NSScrollView而不是推到documentView一边.

在这里你可以看到NSCollectionView我希望100%宽的背景,并让卷轴坐在上面.目前,我必须为滚动条设置白色背景,因为使用a绘制时clearColor不显示为透明,而是显示为黑色.

我是以错误的方式来做这件事的吗？我错过了一些明显的东西吗？如何实现NSScroller位于NSScrollView内容之上的透明跟踪行为？

简单地说,我在界面构建器中有2个视图,其中一个使用界面构建器中的RGB滑块设置为颜色99,99,99.

另一个视图以编程方式着色以实现某种形状.我填写它使用:

//Obviously, this is in drawRect.
[[UIColor leadColor] set];
CGContextEOFillPath(myContext);

//And this is a category on UIColor
+ (UIColor *)leadColor {
    return [UIColor colorWithWhite:99/255.0 alpha:1.0];
}

结果:

为什么存在这种差异？

编辑:( drawRect删除了不必要的代码)

EDIT2:

所以,我在这里骗自己.."界面构建器显示RGB 99,99,99为80,80,80.我打赌它将数字偏移19." >.> ......一个绝望的人使用Xcode认为像这样的疯狂的东西..结果:

完善!!,但为什么 ???? 另一个Xcode错误？我发现过去一个月中有10个......

我正在尝试在我的iOS应用中创建下面的圈子.我知道如何制作圆圈,但我不完全确定如何获得圆弧上的点数.它必须是代码而不是图像.下面是我目前的代码.

 - (void)drawRect:(CGRect)rect
{
    CGPoint point;
    point.x = self.bounds.origin.x + self.bounds.size.width/2;
    point.y = self.bounds.origin.y + self.bounds.size.height/2;

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetLineWidth(context, 2.0);

    CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

    CGRect circle = CGRectMake(point.x/2,point.y-point.x/2,point.x,point.x);

    CGContextAddEllipseInRect(context, circle);

    CGContextStrokePath(context);

    for (int i = 0; i<8; i++) {
        CGRect circleMini = CGRectMake(??????,??????,point.x/4,point.x/4);

        CGContextAddEllipseInRect(context, circleMini);
        CGContextStrokePath(context);
    }

}

更新到答案

 float cita = 0;
for (int i = 0; i<8; i++) {

    CGPoint pointCir = CGPointMake(point.x/2 + radius * cos(cita) , (point.y-point.x/2) + radius * sin(cita) );
    CGRect circleMini = …

我试图将一个褪色UIColor到另一个drawRect.我创建了这个函数来计算某个百分比的颜色:

- (UIColor *)colorFromColor:(UIColor *)fromColor toColor:(UIColor *)toColor percent:(float)percent
{
    float dec = percent / 100.f;
    CGFloat fRed, fBlue, fGreen, fAlpha;
    CGFloat tRed, tBlue, tGreen, tAlpha;
    CGFloat red, green, blue, alpha;

    if(CGColorGetNumberOfComponents(fromColor.CGColor) == 2) {
        [fromColor getWhite:&fRed alpha:&fAlpha];
        fGreen = fRed;
        fBlue = fRed;
    }
    else {
        [fromColor getRed:&fRed green:&fGreen blue:&fBlue alpha:&fAlpha];
    }
    if(CGColorGetNumberOfComponents(toColor.CGColor) == 2) {
        [toColor getWhite:&tRed alpha:&tAlpha];
        tGreen = tRed;
        tBlue = tRed;
    }
    else {
        [toColor getRed:&tRed green:&tGreen blue:&tBlue alpha:&tAlpha];
    }

    red = …

我有几个UIView类都绘制相同的东西,但使用不同的颜色和alpha设置.我试图传递参数,但无法弄清楚如何获得我需要的drawRect部分.

我这样画:

CGRect positionFrame = CGRectMake(widthCoordinate,heightCoordinate,20.9f,16.5f);
DrawHexBlue *hex = [[DrawHexBlue alloc] initWithFrame:positionFrame];
[self.imageView addSubview:hex];

我的DrawHexBlue类是这样的:

- (id)initWithFrame:(CGRect)frame{
self = [super initWithFrame:frame];
if (self)
{
    [self setOpaque:YES];
    [self setBackgroundColor:[UIColor clearColor]];
}
return self;

}

- (void)drawRect:(CGRect)rect{    
UIBezierPath *aPath = [UIBezierPath bezierPath];
[[UIColor whiteColor] setStroke];
[[UIColor blueColor] setFill];

// Set the starting point of the shape.
[aPath moveToPoint:CGPointMake(7, 0)];

// Draw the lines.
[aPath addLineToPoint:CGPointMake(16.2, 0)];
[aPath addLineToPoint:CGPointMake(20.9, 8.7)];
[aPath addLineToPoint:CGPointMake(16.2, 16.5)];
[aPath addLineToPoint:CGPointMake(6.7, 16.5)];
[aPath addLineToPoint:CGPointMake(2.1, 8.7)];
[aPath closePath];

[aPath setLineWidth:1.0f]; …

我是我的UIView课的子类.Xcode(我使用的是4.6.3)自动生成的代码说,

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
}
*/

它在我的脑海中提出了几个问题:

1)为什么空的实现drawRect:会在动画期间导致不良性能.

2)我什么时候应该实施drawRect:.

3)如果我正在实施,drawRect:那么应采取什么措施作为最佳实践的预防措施.

我按照在线教程绘制了一个子类UIView.教程显示了一个带有白色背景的UIView,我通过简单地改变超级的bg颜色来修复它.问题是,当触摸结束时,背景不会保持清晰.我不知道.我只是尝试将填充颜色设置为[uicolor clearcolor]; 不成功.这是我正在使用的代码:

@implementation CachedLIView
{
    UIBezierPath *path;
    UIImage *incrementalImage; // (1)
}

- (id)initWithCoder:(NSCoder *)aDecoder
{
    if (self = [super initWithCoder:aDecoder])
    {
        [self setMultipleTouchEnabled:NO];
        [self setBackgroundColor:[UIColor whiteColor]];
        path = [UIBezierPath bezierPath];
        [path setLineWidth:2.0];
    }
    return self;
}

- (void)drawRect:(CGRect)rect
{
    [incrementalImage drawInRect:rect]; // (3)
    [path stroke];
}


- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    CGPoint p = [touch locationInView:self];
    [path moveToPoint:p];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    CGPoint p …

我正在使用UIView的子类来绘制,这个子类视图用于在视图控制器上获取您的签名.有一个清除按钮,应该清除UIView,除非它不起作用.这是我尝试过的.

subclass.h

@implementation subclassed uiview
{
    UIBezierPath *path;
    UIImage *incrementalImage; // (1)
}

- (id)initWithCoder:(NSCoder *)aDecoder {
    if (self = [super initWithCoder:aDecoder]) {
        [self setMultipleTouchEnabled:NO];
        [self setBackgroundColor:[UIColor clearColor]];
        path = [UIBezierPath bezierPath];
        [path setLineWidth:2.0];
    }
    return self;
}

- (void)drawRect:(CGRect)rect {
    [incrementalImage drawInRect:rect]; // (3)
    [path stroke];
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint p = [touch locationInView:self];
    [path moveToPoint:p];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    CGPoint p …

我试图在android中创建一个类似于结构的家族树.我正在使用画布为家庭成员名称和连接线绘制矩形和线条.

我在链接的帮助下通过以下方法绘制矩形和线条

DrawView.java

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.Log;
import android.view.View;

public class DrawView  extends View {
    Paint paint = new Paint();
    float mx,  my,  mdensity;
    Paint mBGPaint, mTXTPaint,mLINEPaint,mBRDPaint;
    String text;
    public DrawView(Context context, float x, float y, float density, String text) {
        super(context);
        paint.setColor(Color.RED);
        paint.setStrokeWidth(8);
        paint.setStyle(Paint.Style.STROKE);

        mx = x;
        my = y;
        mdensity = density;
        this.text = text;
    }
    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        init();

        mLINEPaint.setStrokeWidth(8);

        //draw rect border
        canvas.drawRect(100, 100, …