Android之自定义View学习（一）
Canvas常用方法：
/**
* Created by SiberiaDante on 2017/6/3.
*/ public class BaseViewDraw extends View {
private Paint mPaint1;
private Paint mPaint2;
private Paint mPaint3;
private Paint mPaint4; public BaseViewDraw(Context context) {
super(context);
} public BaseViewDraw(Context context, AttributeSet attrs) {
super(context, attrs);
initPaint();//初始化画笔
} public BaseViewDraw(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
} private void initPaint() {
mPaint1 = new Paint();
mPaint1.setColor(Color.BLUE);//设置画笔颜色
mPaint1.setStrokeWidth(10f);//设置画笔宽度
mPaint1.setStyle(Paint.Style.FILL);//设置画笔填充模式 mPaint2 = new Paint();
mPaint2.setColor(Color.RED);
mPaint2.setStrokeWidth(20f);
mPaint2.setStyle(Paint.Style.FILL_AND_STROKE); mPaint3 = new Paint();
mPaint3.setColor(Color.BLACK);
mPaint3.setStrokeWidth(15f);
mPaint3.setStyle(Paint.Style.STROKE); mPaint4 = new Paint();
mPaint4.setColor(Color.GREEN);
mPaint4.setStrokeWidth(5f);
mPaint4.setStyle(Paint.Style.STROKE);
} @Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
/**
* 画颜色
* 了解更多canvas前往官方文档：https://developer.android.com/reference/android/graphics/Canvas.html
*/
canvas.drawColor(Color.GRAY);
/**
* 画点
*/
canvas.drawPoint(200, 200, mPaint1);//画一个点----200,200分别代表在想，x,y轴上的坐标
canvas.drawPoints(
new float[]{//画多个点
300, 300,
300, 400,
300, 500
}, mPaint1);
/**
* 画线条
*/
canvas.drawLine(10, 10, 200, 500, mPaint1);//10,10代表起点，200,500代表终点
canvas.drawLines(new float[]{//画多条线段
20, 20, 600, 20,
50, 200, 50, 600}, mPaint1); /**
* 画矩形，三种写法
* 了解更多 Rect前往官方文档:https://developer.android.com/reference/android/graphics/Rect.html
* 了解更多 RectF前往官方文档:http://developer.android.com/reference/android/graphics/RectF.html
*/
//第一种
canvas.drawRect(500, 100, 800, 400, mPaint1);
//第二种
final Rect rect = new Rect(500, 500, 800, 800);
canvas.drawRect(rect, mPaint1);
//第三种
final RectF rectF = new RectF(500, 900, 800, 1200);
canvas.drawRect(rectF, mPaint1);
/**
* 绘制圆角矩形
*/
//方法一
final RectF rectF1 = new RectF(100, 900, 400, 1200);
//10,30分别代表圆弧的半径
canvas.drawRoundRect(rectF1, 10, 30, mPaint2);
//方法二
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
//这种写法仅支持API21+
canvas.drawRoundRect(100, 900, 400, 1200, 10, 30, mPaint2);
} /**
* 画椭圆
* 350为矩形x轴长度的一半
* 150为矩形y轴长度的一半
*/
final RectF rectF2 = new RectF(100, 500, 800, 800);
canvas.drawRoundRect(rectF2, 350, 150, mPaint3); /**
* 画圆
* 350为矩形x轴长度的一半
* 350为矩形y轴长度的一半
* 当矩形的长和宽相等时，即为圆
*/
//方法一：利用矩形绘制椭圆技巧
final RectF rectF3 = new RectF(100, 500, 800, 1200);
canvas.drawRoundRect(rectF3, 350, 350, mPaint3);
//方法二：550,800代表圆心位置，400代表圆半径
canvas.drawCircle(550, 800, 400, mPaint3); /**
* 画圆弧
* 0,90分别代表弧度的起始和结束弧度，顺时针为正，区分数学中的逆时针为正
* 第三个Boolean型参数：true为使用中心点，false为不使用中心点，即为一段弧线（不填充状态下）
*/
final RectF rectF4 = new RectF(400, 400, 800, 1200);
canvas.drawArc(rectF4, 0, 90, true, mPaint4); final RectF rectF5 = new RectF(100, 400, 400, 1200);
canvas.drawArc(rectF5, 0, 90, false, mPaint4); }
}