我想创建一个逐渐从一种颜色变为另一种颜色的弧线(可变度数)。从例如,从蓝色到红色:
Android - 如何绘制基于渐变的弧线
这是我的代码:
SweepGradient shader = new SweepGradient(center.x, center.y, resources.getColor(R.color.startColor),resources.getColor(R.color.endColor));
Paint paint = new Paint()
paint.setStrokeWidth(1);
paint.setStrokeCap(Paint.Cap.FILL);
paint.setStyle(Paint.Style.FILL);
paint.setShader(shader);
canvas.drawArc(rectF, startAngle, sweepAngle, true, paint);
但结果是整个弧绘有相同的颜色。
编辑:
更多经过试验,我发现,颜色传播是由弧形的角度来确定。如果我绘制一个小角度的弧线,只显示第一种颜色。角度越大,画出的颜色越多。如果角度很小,似乎没有梯度。
这里是一个例子。我画弧4 - 90,180,270和360:
RectF rect1 = new RectF(50, 50, 150, 150);
Paint paint1 = new Paint();
paint1.setStrokeWidth(1);
paint1.setStrokeCap(Paint.Cap.SQUARE);
paint1.setStyle(Paint.Style.FILL);
SweepGradient gradient1 = new SweepGradient(100, 100,
Color.RED, Color.BLUE);
paint1.setShader(gradient1);
canvas.drawArc(rect1, 0, 90, true, paint1);
RectF rect2 = new RectF(200, 50, 300, 150);
Paint paint2 = new Paint();
paint2.setStrokeWidth(1);
paint2.setStrokeCap(Paint.Cap.SQUARE);
paint2.setStyle(Paint.Style.FILL);
SweepGradient gradient2 = new SweepGradient(250, 100,
Color.RED, Color.BLUE);
paint2.setShader(gradient2);
canvas.drawArc(rect2, 0, 180, true, paint2);
RectF rect3 = new RectF(50, 200, 150, 300);
Paint paint3 = new Paint();
paint3.setStrokeWidth(1);
paint3.setStrokeCap(Paint.Cap.SQUARE);
paint3.setStyle(Paint.Style.FILL);
SweepGradient gradient3 = new SweepGradient(100, 250,
Color.RED, Color.BLUE);
paint3.setShader(gradient3);
canvas.drawArc(rect3, 0, 270, true, paint3);
RectF rect4 = new RectF(200, 200, 300, 300);
Paint paint4 = new Paint();
paint4.setStrokeWidth(1);
paint4.setStrokeCap(Paint.Cap.SQUARE);
paint4.setStyle(Paint.Style.FILL);
SweepGradient gradient4 = new SweepGradient(250, 250,
Color.RED, Color.BLUE);
paint4.setShader(gradient4);
canvas.drawArc(rect4, 0, 360, true, paint4);
这里是结果:
这是令人惊讶的,因为我期望的RED是在弧线的起点,末端的蓝色以及两者之间的角度均匀分布,无论角度如何。
我试图空间的颜色使用手动位置参数,但结果是一样的:
int[] colors = {Color.RED, Color.BLUE};
float[] positions = {0,1};
SweepGradient gradient = new SweepGradient(100, 100, colors , positions);
不知道如何解决这个问题?
至少在Android 4.2中,给出的解决方案不起作用。在数组的末尾需要有一个值1。 类似这样的: int [] colors = {Color.RED,Color.BLUE,Color.BLUE}; float [] positions = {0,Xf/360f,1}; – 2013-05-11 07:19:04
你知道为什么分辨率如此糟糕,如果角度很小?就像10度的弧度意味着只有3种颜色。你可以在你的屏幕截图中看到这些步骤 – 2016-04-05 15:37:23