本篇文章为大家展示了怎么在Android应用中利用View实现一个旋转功能，内容简明扼要并且容易理解，绝对能使你眼前一亮，通过这篇文章的详细介绍希望你能有所收获。
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1、添加右侧旋转
Bitmap turnBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.fengshan, null)).getBitmap();
int turnLeafAngle = 0;
private void setTurnLeaf(Canvas canvas) {
Matrix matrix = new Matrix();
turnLeafAngle = turnLeafAngle + 3;
matrix.postTranslate((width - rightCircleWidth/2 - turnBitmap.getWidth()/2),
(height - rightCircleWidth/2 - turnBitmap.getHeight()/2));
matrix.postRotate(turnLeafAngle,
width - rightCircleWidth/2 - turnBitmap.getWidth()/2 + turnBitmap.getWidth()/2,
height - rightCircleWidth/2 - turnBitmap.getHeight()/2 + turnBitmap.getHeight()/2);
canvas.drawBitmap(turnBitmap, matrix, new Paint());
}代码很明确,首先通过Matrix.postTranslate(float dx, float dy)把turnBitMap定位到最右侧圆圈
再通过Matrix.postRotate(float degress, float dx, float dy);设置旋转角度，每次角度+3°
其中degress为旋转角度，(dx，dy)为旋转中心点坐标
2、添加滑动效果
a、定义一个圆形Rectf（为什么不是半圆？因为画圆弧的其实角度从水平线右侧开始）
progressArcRectf = new RectF(0, 0, height, height);
b、定义一个长方形Rectf,长方形x坐标起点即时圆形半径
progressRectf = new RectF(height/2, 0, width, height);
c、画出圆弧Canvas.drawArc(Rectf rectf, float startAngle, float sweepAngle, boolean useCenter, Paint paint)
startAngle：起始角度，默认从右侧水平线开始
sweepAngle：为旋转的角度，顺时针旋转
useCenter：true只画出弧线，false则画出圆心到弧线的区域
//画滑动后的背景条
int currentProgressWidht = currentProgress * (width - borderWidth)/100;
if(currentProgressWidht < leftCircleWidth/2) {
//angle取值范围0~90
int angle = 90 * currentProgressWidht / (leftCircleWidth/2);
// 起始的位置
int startAngle = 180 - angle;
// 扫过的角度
int sweepAngle = 2 * angle;
canvas.drawArc(progressArcRectf, startAngle, sweepAngle, false, progressBgPaint);
}else {
//画左边半圆形滑过部分
canvas.drawArc(progressArcRectf, 90, 180, false, progressBgPaint);
progressRectf.left = borderWidth + leftCircleWidth/2;
progressRectf.right = borderWidth + currentProgressWidht;
//画中间滑过部分
canvas.drawRect(progressRectf, progressBgPaint);
}给LeafView.java添加一个
public void setCurrentProgress(int currentProgress) {
this.currentProgress = currentProgress;
}3、修复叶子飘动范围
这个简单，就是设置叶子的rect坐标起点+边框距离
赋上所有代码
1、activity_leaf.xml
2、LeafView.java
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import java.util.LinkedList;
import java.util.List;
import java.util.Random;
import java.util.jar.Attributes;
/**
* Created by jiemiao.zhang on 2017-3-15.
*/
public class LeafView extends View {
private String TAG = "--------LeafView";
private Resources mResources;
//背景图、叶子
private Bitmap mLeafBitmap, bgBitmap, turnBitmap;
//整个控件的宽度和高度
private int width, height;
//最外层边框宽度
private int borderWidth;
//右侧圆形直径
private int rightCircleWidth;
//左侧圆形直径
private int leftCircleWidth;
private Paint bgPaint;
private RectF bgRect;
private Rect bgDestRect;
//进度条实时背景
private Paint progressBgPaint;
//进度条左侧半圆，进度条中间长方形部分Rect
private RectF progressArcRectf, progressRectf;
//当前百分比0~100
private int currentProgress = 0;
//存放叶子lsit
private List leafList;
//叶子的宽和高
private int mLeafWidth, mLeafHeight;
//叶子滑动一周的时间5秒
private final static long cycleTime = 5000;
//叶子数量
private final static int leafNumber = 6;
public LeafView(Context context, AttributeSet attrs) {
super(context, attrs);
mResources = getResources();
mLeafBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.leaf, null)).getBitmap();
mLeafWidth = mLeafBitmap.getWidth();
mLeafHeight = mLeafBitmap.getHeight();
turnBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.fengshan, null)).getBitmap();
bgBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.leaf_kuang, null)).getBitmap();
bgPaint = new Paint();
bgPaint.setColor(mResources.getColor(R.color.bg_color));
//进度条实时背景
progressBgPaint = new Paint();
progressBgPaint.setColor(mResources.getColor(R.color.progress_bg_color));
//获取所有叶子的信息，放入list
leafList = getLeafs(leafNumber);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
width = w;
height = h;
borderWidth = height * 10/64;
rightCircleWidth = width * 62/303;
leftCircleWidth = height - 2 * borderWidth;
bgDestRect = new Rect(0, 0 , width, height);
bgRect = new RectF(0, 0 , width, height);
progressArcRectf = new RectF(borderWidth, borderWidth, height - borderWidth, height - borderWidth);
progressRectf = new RectF(borderWidth+(height-2*borderWidth)/2, borderWidth,
width-rightCircleWidth/2, height-borderWidth);
Log.i("leftMarginWidth", (borderWidth + leftCircleWidth/2) + "");
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//画背景颜色到画布
canvas.drawRect(bgRect, bgPaint);
if(currentProgress <= 100) {
//画叶子
int size = leafList.size();
for (int i=0; i 3) {
canvas.drawText(currentProgress + "%", textX, height/2 + 10,paintText);
}
}
//获取每片叶子在XY轴上的滑动值
private void getLocation(Leaf leaf) {
float betweenTime = leaf.startTime - System.currentTimeMillis();
//周期结束再加一个cycleTime
if(betweenTime < 0) {
leaf.startTime = System.currentTimeMillis() + cycleTime + new Random().nextInt((int) (cycleTime));
betweenTime = cycleTime;
}
//通过时间差计算出叶子的坐标
float fraction = (float) betweenTime / cycleTime;
float x = (int)(width * fraction);
//防止叶子飘出边框
leaf.x = x < borderWidth ? borderWidth : x;
float w = (float) ((float) 2 * Math.PI / width);
int y = (int) (18 * Math.sin(w * x)) + (height-mLeafHeight)/2;
//防止叶子飘出边框
y = y > (height - borderWidth) ? (height - borderWidth) : y;
y = y < borderWidth ? borderWidth : y;
leaf.y = y;
}
//获取每片叶子的旋转角度
private void getRotate(Leaf leaf) {
float scale = ((leaf.startTime - System.currentTimeMillis())%cycleTime)/ (float)cycleTime;
int rotate = (int)(scale * 360);
leaf.rotateAngle = rotate;
}
private class Leaf {
// 叶子的坐标
float x, y;
// 旋转角度
int rotateAngle;
// 起始时间(ms)
long startTime;
}
private List getLeafs(int leafSize) {
List list = new LinkedList();
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