Android 自定义View-Canvas
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了Android 自定义View-Canvas，小编现在分享给大家，供广大互联网技能从业者学习和参考。文章包含3786字，纯文字阅读大概需要6分钟。
内容图文
文章目录
Canvas的使用
Paint简单介绍
画笔，用于绘制内容的具体效果，如：颜色、文字大小、线条粗细、阴影，实心空心等。
常用API
Paint.setStyle(Style style) 设置绘制模式
Style 具体来说有三种： FILL, STROKE 和 FILL_AND_STROKE 。FILL 是填充模式，STROKE 是画线模式（即勾边模式
Paint.setColor(int color) 设置颜色
Paint.setStrokeWidth(float width) 设置线条宽度
Paint.setTextSize(float textSize) 设置文字大小
Paint.setAntiAlias(boolean aa) 设置抗锯齿开关
Canvas绘制
drawColor 绘制颜色
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//canvas.drawColor(Color.GREEN);
//canvas.drawColor(Color.parseColor("#88880000"));
canvas.drawRGB(100, 200, 100);
//canvas.drawARGB(100, 100, 200, 100);
}
drawCircle 绘制圆形
private void init() {
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.RED);
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setStyle(Paint.Style.FILL);
//圆心坐标，半径，画笔
canvas.drawCircle(110, 110, 100, paint);
paint.setStrokeWidth(10);
paint.setStyle(Paint.Style.STROKE);
canvas.drawCircle(110, 320, 100, paint);
}
drawRect 绘制矩形
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setStyle(Paint.Style.FILL);
//左上右下四个顶点坐标，画笔
canvas.drawRect(100, 100, 200, 200, paint);
paint.setStrokeWidth(10);
paint.setStyle(Paint.Style.STROKE);
canvas.drawRect(100, 250, 200, 350, paint);
}
drawRoundRect 绘制圆角矩形
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setStyle(Paint.Style.FILL);
//左上右下四个顶点，圆角半径
canvas.drawRoundRect(100, 100, 500, 300, 50, 50, paint);
paint.setStrokeWidth(10);
paint.setStyle(Paint.Style.STROKE);
canvas.drawRoundRect(100, 400, 500, 600, 50, 50, paint);
}
drawPoint 绘制点
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setStrokeWidth(20);
//点的样式
paint.setStrokeCap(Paint.Cap.ROUND);
//点的坐标，画笔
canvas.drawPoint(100, 100, paint);
paint.setStrokeWidth(20);
paint.setStrokeCap(Paint.Cap.SQUARE);
canvas.drawPoint(150, 150, paint);
}
drawPoints 绘制多个点
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setStrokeWidth(20);
paint.setStrokeCap(Paint.Cap.ROUND);
float[] points = {10, 10, 50, 50, 100, 100, 150, 150, 200, 200};
//所有点坐标，跳过前几个，一共绘制8个数（4个点）
canvas.drawPoints(points, 2, 8, paint);
}
drawOval 绘制椭圆
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setStyle(Paint.Style.FILL);
//左上右下四个坐标
canvas.drawOval(50, 100, 250, 250, paint);
paint.setStyle(Paint.Style.STROKE);
canvas.drawOval(50, 300, 250, 450, paint);
}
drawArc 绘制弧线或扇形
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//左上右下四个顶点
RectF rectF = new RectF(100F, 100F, 400F, 300F);
//设置填充模式
paint.setStyle(Paint.Style.FILL);
//startAngle：弧形开始角度，sweepAngle：弧形划过角度
//useCenter：是否连接圆心
canvas.drawArc(rectF, -100, 100, true, paint);
canvas.drawArc(rectF, 30, 90, false, paint);
paint.setStyle(Paint.Style.STROKE);
canvas.drawArc(rectF, 130, 50, false, paint);
}
drawLine 绘制线
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setStrokeWidth(20);
canvas.drawLine(200, 200, 500, 500, paint);
}
drawLines 绘制多条线
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setStrokeWidth(5);
float[] points = {20, 20, 120, 20, 70, 20, 70, 100, 20, 100, 120, 100};
canvas.drawLines(points, paint);
}
drawBitmap 绘制Bitmap
canvas.drawBitmap(bitmap, 200, 200, new Paint());
drawText 绘制文本
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setTextSize(30);
canvas.drawText("hello", 100, 100, paint);
}
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