android 自定义view 类似loadding从下往上加载的动画

package com.nbhero.DIYview;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

import com.nbhero.flower.R;
import com.nbhero.util.tool;

/**
* Created by zhenglingzhong on 2016/11/8.
*/

public class AboutGas extends View{

//view
private  int viewheight;
private  int viewwidth;
private  Paint paintbit;
private  Bitmap mybit;
private  int bitWidth;
private  int bitHeight;
private PorterDuffXfermode mXfermode;
private Rect mSrcRect, mDestRect,mDynamicRect;
private  Paint mBitPaint;

private  float move = 0.5f;

public AboutGas(Context context) {
this(context,null);
}

public AboutGas(Context context, AttributeSet attrs) {
this(context, attrs,0);
}

public AboutGas(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

viewheight = View.MeasureSpec.getSize(heightMeasureSpec);
viewwidth = View.MeasureSpec.getSize(widthMeasureSpec);
if (viewheight > viewwidth){
viewheight = viewwidth;
}
setMeasuredDimension(viewwidth, viewheight);
init();

}

private  void init(){

mXfermode = new PorterDuffXfermode(PorterDuff.Mode.SRC_IN);
//画笔
paintbit = new Paint(Paint.ANTI_ALIAS_FLAG);
paintbit.setFilterBitmap(true);
paintbit.setDither(true);
paintbit.setAntiAlias(true);
paintbit.setColor(Color.YELLOW);
//图像对象
mybit = ((BitmapDrawable) getResources().getDrawable(R.drawable.gastudio))
.getBitmap();
bitWidth = mybit.getWidth();
bitHeight = mybit.getHeight();
Log.e("zlz","width" + bitWidth);
Log.e("zlz","bitHeight" + bitHeight);
int rawHeight = bitHeight;
int rawWidth = bitWidth;
// 设定图片新的高宽
int newHeight = viewwidth;
// 计算缩放因子
float heightScale = ((float) newHeight) / rawHeight;

// 新建立矩阵
Matrix matrix = new Matrix();
matrix.postScale(heightScale, heightScale);

mybit = Bitmap.createBitmap(mybit, 0, 0, rawWidth,
rawHeight, matrix, true);

bitWidth = mybit.getWidth();
bitHeight = mybit.getHeight();
Log.e("zlz","width" + bitWidth);
Log.e("zlz","bitHeight" + bitHeight);
Log.e("zlz","viewidth" + viewwidth);
Log.e("zlz","viewheight" + viewheight);
mSrcRect = new Rect(0,0,bitWidth,bitHeight);

mDestRect = new Rect(bitHeight / 2 - bitWidth / 2,0,bitHeight / 2 - bitWidth / 2 + bitWidth,bitHeight);
mDynamicRect = new Rect(bitHeight / 2 - bitWidth / 2,bitHeight,bitHeight / 2 - bitWidth / 2 + bitWidth,bitHeight);

}

@Override
protected void onDraw(Canvas canvas) {
mBitPaint = new Paint();
mBitPaint.setColor(Color.YELLOW);
int saveLayerCount = canvas.saveLayer(0, 0, viewwidth, viewwidth, mBitPaint,
Canvas.ALL_SAVE_FLAG);
canvas.drawBitmap(mybit,mSrcRect,mDestRect,paintbit);
mBitPaint.setXfermode(mXfermode);
// 绘制源图形

canvas.drawRect(mDynamicRect, mBitPaint);
if(mDynamicRect.top >= (int)((1-move) * (float) bitHeight)){
Log.e("zlz","mDynamicRect.top " + mDynamicRect.top );
mDynamicRect.top -= 2;
postInvalidate();
}
}

public  void setGas(float gas){

this.move = gas;

}

private  Bitmap makeBit(){

//得到图片原始的高宽
int rawHeight = bitHeight;
int rawWidth = bitWidth;
// 设定图片新的高宽
int newHeight = viewwidth;
// 计算缩放因子
float heightScale = ((float) newHeight) / rawHeight;
// 新建立矩阵
Matrix matrix = new Matrix();
matrix.postScale(heightScale, heightScale);
// 设置图片的旋转角度
// matrix.postRotate(-30);
// 设置图片的倾斜
// matrix.postSkew(0.1f, 0.1f);
// 将图片大小压缩
// 压缩后图片的宽和高以及kB大小均会变化
Bitmap newBitmap = Bitmap.createBitmap(mybit, 0, 0, rawWidth,
rawHeight, matrix, true);

return  newBitmap;

}
}