Android原生绘图工具Paint详细
前言:
生活中绘制图案需要纸和笔，android中提供了类似的工具Canvas和Paint，分别对应画布和画笔。
The Paint class holds the style and color information about how to draw geometries, text and bitmaps.
Paint拥有绘制几何图形、文本、图片的样式和颜色信息。
The Canvas class holds the "draw" calls. To draw something, you need 4 basic components: A Bitmap to hold the pixels, a Canvas to host the draw calls (writing into the bitmap), a drawing primitive (e.g. Rect, Path, text, Bitmap), and a paint (to describe the colors and styles for the drawing).
Canvas拥有绘图的请求权，想要完成绘制，需要4个基本元素：保存像素的Bitmap、一个可以调用draw方法的canvas、要绘制的内容描述、一个画笔。凭借这4个元素就可以绘制到一个bitmap上，然后渲染到屏幕上。
1.简介
今天先将一下Paint的相关内容。Paint提供了三种初始化方法：
Paint() Paint(int flag) Paint(Paint paint)
2.基本属性使用
2.1 setAlpha透明度
setAlpha(int a) 设置范围0~255
2.2 setStyle填充样式
填充样式表示绘线和填充的选择：
Paint.Style.FILL Paint.Style.FILL_AND_STROKE Paint.Style.STROKE
2.3 颜色，字体，对齐，抗锯齿
setColor，setARGB设置颜色，设置画笔的颜色，
setARGB（）参数范围0-255。
setAntiAlias（boolean） 抗锯齿，使边界更顺滑（有些屏幕分辨率不高，导致像素点比较大，绘制边界可能会有颗粒感，打开抗锯齿边界颗粒感会减少）。
setTextSize(float textSize) 字体大小，单位是px，如果是dp要注意转换。
setTextAlign(Paint.Align.RIGHT)设置字体对齐方式，根据下面的实例可以，对齐方式基于开始绘制的点。
mTextPaint.setTextAlign(Paint.Align.LEFT);
canvas.drawText("MatumbaMan的博客",200, 200, mTextPaint);
mTextPaint.setTextAlign(Paint.Align.RIGHT);
canvas.drawText("MatumbaMan的博客",200, 300, mTextPaint);
mTextPaint.setTextAlign(Paint.Align.CENTER);
canvas.drawText("MatumbaMan的博客",200, 400, mTextPaint);
2.4 setShadowLayer 阴影
setShadowLayer(float radius, float dx, float dy, int shadowColor) 设置阴影
Radius设置角度，dx，dy控制字体的上下左右出现，有正负之分，dx的正负代表右左，dy的正负代表下上。
mTextPaint.setTextAlign(Paint.Align.LEFT);
mTextPaint.setShadowLayer(10, -20, 40, Color.GRAY);
canvas.drawText("MatumbaMan的博客",200, 200, mTextPaint);
mTextPaint.setTextAlign(Paint.Align.RIGHT);
canvas.drawText("MatumbaMan的博客",200, 300, mTextPaint);
mTextPaint.setTextAlign(Paint.Align.CENTER);
canvas.drawText("MatumbaMan的博客",200, 400, mTextPaint);
2.5 setStrokeCap
setStrokeCap(Paint.Cap.ROUND)设置绘制起始点和结尾点的样式，
三种样式ROUND,BUTT,SQUARE、
Cap.ROUND(圆形)
Cap.SQUARE(方形)
Paint.Cap.BUTT(无)
Path path = new Path(); path.moveTo(100, 100); path.lineTo(100, 200); path.lineTo(200, 300); canvas.drawPath(path, mPaint2);//无 path.reset(); path.moveTo(300, 100); path.lineTo(300, 200); path.lineTo(400, 300); mPaint2.setStrokeCap(Paint.Cap.ROUND);//圆 canvas.drawPath(path, mPaint2); path.reset(); path.moveTo(500, 100); path.lineTo(500, 200); path.lineTo(600, 300); mPaint2.setStrokeCap(Paint.Cap.SQUARE);//方 canvas.drawPath(path, mPaint2);
2.6 setStrokeJoin
setStrokeJoin(Paint.Join join)，设置绘制path连接点的样式
Join.MITER（结合处为锐角）
Join.Round(结合处为圆弧)
Join.BEVEL(结合处为直线)
Path path = new Path(); path.moveTo(100, 100); path.lineTo(100, 200); path.lineTo(200, 300); mPaint2.setStrokeJoin(Paint.Join.MITER); canvas.drawPath(path, mPaint2); path.reset(); path.moveTo(300, 100); path.lineTo(300, 200); path.lineTo(400, 300); mPaint2.setStrokeJoin(Paint.Join.ROUND); canvas.drawPath(path, mPaint2); path.reset(); path.moveTo(500, 100); path.lineTo(500, 200); path.lineTo(600, 300); mPaint2.setStrokeJoin(Paint.Join.BEVEL); canvas.drawPath(path, mPaint2);
上一篇：Android用SharedPreferences实现登录注册注销功能
栏 目：Android代码
本文标题：Android原生绘图工具Paint详细
本文地址：http://www.codeinn.net/misctech/219126.html
