Android 自定义图片进度条

用系统的Progressbar，设置图片drawable作为进度条会出现图片长度不好控制，容易被截断，或者变形的问题。而我有个需求，使用图片背景，和图片进度，而且在进度条头部有个闪光点效果。

如下图：

找了两个小时，国内外，百度，github搜遍了，全网都没有找到一个现成的。

最后只好自己写一个。本来我用自己代码写的用颜色值的进度条，很容易就实现了。

产品要用设计师的图片。谁知道啊，这么个小功能却这么麻烦，为这么个进度条的功能加班到晚上11点。

package com.alisajidapps.watermarkpdfss.view;import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.View;import com.alisajidapps.watermarkpdfss.R;public class CustomProgressBar extends View {private Paint paint;private Bitmap progressBarImage;private Bitmap backgroundImage;private Bitmap progressPointerBitmap;private Rect srcRect;private Rect dstRect;private int progress;//手机宽度private int screenWidth;private int progressWidth;private int progressHeight;//缩放后的进度条宽度private int progressBarWidthNew;private Rect pointerRect;private Rect pointerDstRect;public CustomProgressBar(Context context) {super(context);init();}public CustomProgressBar(Context context, AttributeSet attrs) {super(context, attrs);init();}public CustomProgressBar(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);init();}private void init() {paint = new Paint();progressBarImage = BitmapFactory.decodeResource(getResources(), R.drawable.update_progress); // 你的进度条图片资源backgroundImage = BitmapFactory.decodeResource(getResources(), R.drawable.update_progress_bg); // 你的进度条图片资源progressPointerBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.update_progress_seek); // 你的进度条图片资源DisplayMetrics displayMetrics = getResources().getDisplayMetrics();screenWidth = displayMetrics.widthPixels;scale = (float) (screenWidth*0.7/backgroundImage.getWidth());progressWidth =  progressBarImage.getWidth();progressHeight = progressBarImage.getHeight();progressBarWidthNew = (int) (progressBarImage.getWidth()*scale);srcRect = new Rect();dstRect = new Rect();backRect=new Rect();backDstRect=new Rect();pointerRect = new Rect();pointerDstRect = new Rect();progress =10;}public void setProgress(int progress) {this.progress = progress;invalidate(); // 重绘视图}Rect backRect;Rect backDstRect;float scale;@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);Log.e("xxx","scrrenWidth："+screenWidth);//第一步，画背景backRect.left =0;backRect.top = 0;backRect.right = backgroundImage.getWidth();backRect.bottom = backgroundImage.getHeight();Log.e("xxx",scale+"");Log.e("xxx","backgroundImageWidth:"+backgroundImage.getWidth()+"");backDstRect.top =20;backDstRect.left = (int) (screenWidth/2 - (backgroundImage.getWidth() * scale/2));backDstRect.right = (int) (screenWidth/2 + (backgroundImage.getWidth() * scale/2));backDstRect.bottom = (int) (backgroundImage.getHeight() * scale)+20;// 绘制缩放后的位图，dstRect缩放后，画进去的图片就是缩放的。canvas.drawBitmap(backgroundImage, backRect, backDstRect, paint);//第二步，画进度条srcRect.left = 0;srcRect.top = 0;srcRect.right = progressWidth;srcRect.bottom = progressHeight;Log.e("xxx","progressWidth:"+progressWidth);Log.e("xxx","progressHeight:"+progressHeight);Log.e("xxx","progressbarWidth:"+progressBarImage.getWidth());progressWidth = (int) (progressBarWidthNew *progress / 100 ); // 假设进度是0到100//dstRect  等比例缩放了，画进去的图片就会等比例缩放dstRect.top =30;dstRect.left = (int) (screenWidth/2 -  progressBarWidthNew/2);dstRect.right = dstRect.left+ progressWidth;dstRect.bottom = (int) (progressBarImage.getHeight() * scale+30);canvas.drawBitmap(progressBarImage, srcRect, dstRect, paint);Log.e("xxx","怎么没有绘制:"+progressWidth);//第三步，画进度条前面的指针效果pointerRect.left = 0;pointerRect.top = 0;pointerRect.right = progressPointerBitmap.getWidth();pointerRect.bottom = progressPointerBitmap.getHeight();pointerDstRect.left = dstRect.right-15;pointerDstRect.top = 0;pointerDstRect.right = (int) (dstRect.right+ progressPointerBitmap.getWidth()*scale-15);pointerDstRect.bottom = (int) (progressPointerBitmap.getHeight()*scale);canvas.drawBitmap(progressPointerBitmap,pointerRect,pointerDstRect,paint);}
}

使用时只需要调用setProgressBar就行。

上图就是代码实现的效果。

知识总结：

1，基本的绘制图片方法

drawBitmap(Bitmap bitmap, float left, float top, Paint paint)

参数：//Bitmap：图片对象，left:偏移左边的位置，top：偏移顶部的位置

2， drawBitmap( Bitmap bitmap, Rect src, Rect dst, Paint paint)；

这里由2个Rect，第一个Rect --src 代表要裁剪的bitmap的区域，如传null,表示需要绘制整个图片，

第二个Rect ---det表示需要将bitmap，绘制在屏幕上的位置，不可为空，并且大于src则把src的裁截区放大，小于src则把src的裁截区缩小。

Bitmap bitmap = BitmapFactory.decodeResource(getContext().getResources(),R.drawable.ic_logo);

//绘制方法1：---原图，制作偏移

canvas.drawBitmap(bitmap,100,100,mPaint);//将图片从（0，0）位置向左偏移100，向右偏移100