android学习日记08--Paint画笔

Paint

　　要绘图，首先得调整画笔，待画笔调整好之后，再将图像绘制到画布Canvas上，
这样才可以显示在手机屏幕上。Android 中的画笔是 Paint类，Paint 中包含了很多方法对其属性进行设置，

Paint方法一般可分两类，图形的绘制和文本的绘制
主要方法如下：（没有全部列出，大家可以查看官方文档http://android.toolib.net/reference/android/graphics/Paint.html ）

                canvas.drawColor(Color.GREEN);
                
                Paint paint1 = new Paint();
                canvas.drawCircle(40, 30, 20, paint1);
                
                //设置画笔无锯齿，默认有锯齿
                paint1.setAntiAlias(true);
                canvas.drawCircle(100, 30, 20, paint1);
                
                //设置画笔的透明度
                canvas.drawText("无透明度", 100, 70, new Paint());
                Paint paint2 = new Paint();
                paint2.setAlpha(0x77);
                canvas.drawText("半透明度", 20, 70, paint2);
                
                //设置绘制文本的锚点
                canvas.drawText("锚点", 20, 90, new Paint());
                Paint paint3 = new Paint();
                
                //设置以文本的中心点绘制
                paint3.setTextAlign(Paint.Align.CENTER);
                canvas.drawText("锚点", 20, 105, paint3);
                
                //获取文本的长度
                Paint paint4 = new Paint();
                float len =paint4.measureText("文本宽度:");
                canvas.drawText("文本长度:"+len, 20, 130, new Paint());
                
                //设置画笔样式
                canvas.drawRect(new Rect(20,140,40,160), new Paint());
                Paint paint5 = new Paint();
                
                //设置画笔不填充
                paint5.setStyle(Style.STROKE);
                canvas.drawRect(new Rect(60,140,80,160), paint5);
                
                //设置画笔颜色
                Paint paint6 = new Paint();
                paint6.setColor(Color.GRAY);
                canvas.drawText("灰色", 30, 180, paint6);
                
                //设置画笔的粗细程度
                canvas.drawLine(20, 200,70, 200, new Paint());
                Paint paint7 = new Paint();
                paint7.setStrokeWidth(7);
                canvas.drawLine(20, 220,70, 220,paint7);
                
                //设置画笔绘制文本的字体粗细
                Paint paint8 = new Paint();
                paint8.setTextSize(20);
                canvas.drawText("文字尺寸", 20, 260, paint8);
                
                //设置画笔的ARGB分量 ，a值 (透明度)
                Paint paint9 = new Paint();
                paint9.setARGB(0x77, 0xff, 0x00, 0x00);
                canvas.drawText("红色半透明", 20, 290, paint9);