自定義ImageView系列 － 區(qū)域截圖（下）
功能要點(diǎn)：
- 根據(jù)控件自身大小計(jì)算合適的透明正方形預(yù)覽區(qū)荆虱；
- 截取預(yù)覽區(qū)圖像并按照指定的尺寸縮放君编，生成Bitmap對(duì)象。
本文著重介紹上述第2個(gè)要點(diǎn)。
有關(guān)第一個(gè)要點(diǎn)的內(nèi)容岳瞭，請(qǐng)參閱上一篇文章：請(qǐng)點(diǎn)此歧焦。
本篇文章中我們主要聊兩個(gè)問(wèn)題：
- 屏幕指定區(qū)域截圖签赃；
- 圖片縮放哨坪。
由于在前文中，我們知道了指定區(qū)域的方位，那么解決起來(lái)就輕松很多了两嘴。只要先截取整個(gè)屏幕丛楚，然后利用Matrix將圖片進(jìn)行裁剪即可。
截取到指定部分的圖像后憔辫，再利用Matrix的postScale()方法即可進(jìn)行縮放趣些。
下面放上代碼片段：
public Bitmap getAdjustedBitmap(Activity activity) {
View view = activity.getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache();
bitmap = view.getDrawingCache();
matrix = new Matrix();
matrix.postScale((CommonSettings.AVATOR\_SIZE * 1.0f) / (previewEdge[1] - previewEdge[0]), (CommonSettings.AVATOR\_SIZE * 1.0f) / (previewEdge[1] - previewEdge[0]));
return Bitmap.createBitmap(bitmap, previewEdge[0] - 2, previewEdge[2] + myLocationStart[1] - 2, previewEdge[1] - previewEdge[0], previewEdge[1] - previewEdge[0], matrix, false);
}
如上所示，即可完成截圖和縮放操作贰您。
接下來(lái)放上整個(gè)重寫的ImageView類的代碼坏平，這里面還包含了雙指縮放和單指移動(dòng)操作功能。
package com.toec.acryptim.view;
import android.app.Activity;
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.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import com.toec.acryptim.R;
import com.toec.acryptim.environment.CommonSettings;
/**
* 作者：蕭文翰
* 郵箱：wh1990xiao2005@hotmail.com
* 移動(dòng)電話：+86 15822932537
* 微博：http://weibo.com/xwhnew
* 個(gè)人網(wǎng)站：http://www.xwhcoder.com
*/
public class PhotoChooseForAvatorImageView extends ImageView {
private Bitmap bitmap;
private Matrix matrix;
private float point1_old_x, point1_old_y, point1_new_x, point1_new_y,
point2_old_x, point2_old_y, point2_new_x, point2_new_y,
distance_old, distance_new;
private float point_old_x, point_old_y, point_new_x, point_new_y;
private boolean isMultiTouch = false;
private int[] myLocationStart;
private int[] myLocationEnd;
private int[] myLocationMid;
private int[] previewEdge;
private int bitmapLocXStart, bitmapLocXEnd, bitmapLocYStart, bitmapLocYEnd;
private Paint rectPaint;
private Paint rectBgPaint;
public PhotoChooseForAvatorImageView(Context context) {
super(context);
if (matrix == null) {
matrix = new Matrix();
}
}
public PhotoChooseForAvatorImageView(Context context, AttributeSet attrs) {
super(context, attrs);
if (matrix == null) {
matrix = new Matrix();
}
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
if (bitmap != null) {
canvas.drawBitmap(bitmap, matrix, null);
}
if (previewEdge != null) {
//上
canvas.drawLine(previewEdge[0], previewEdge[2], previewEdge[1], previewEdge[2], rectPaint);
//左
canvas.drawLine(previewEdge[0], previewEdge[2], previewEdge[0], previewEdge[3], rectPaint);
//下
canvas.drawLine(previewEdge[0], previewEdge[3], previewEdge[1], previewEdge[3], rectPaint);
//右
canvas.drawLine(previewEdge[1], previewEdge[2], previewEdge[1], previewEdge[3], rectPaint);
//灰色部分
canvas.drawRect(0, 0, previewEdge[0], myLocationEnd[1], rectBgPaint);
canvas.drawRect(previewEdge[0], 0, previewEdge[1], previewEdge[2], rectBgPaint);
canvas.drawRect(previewEdge[1], 0, myLocationEnd[0], myLocationEnd[1], rectBgPaint);
canvas.drawRect(previewEdge[0], previewEdge[3], previewEdge[1], myLocationEnd[1], rectBgPaint);
}
canvas.restore();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
// 單點(diǎn)移動(dòng) 按下
if (event.getPointerCount() == 1) {
isMultiTouch = false;
point_old_x = event.getX();
point_old_y = event.getY();
}
break;
case MotionEvent.ACTION_UP:
// 單點(diǎn)移動(dòng) 抬起
if (event.getPointerCount() == 1) {
isMultiTouch = false;
point_old_x = point_new_x;
point_old_y = point_new_y;
}
break;
case MotionEvent.ACTION_POINTER_UP:
// 雙點(diǎn)操作 抬起
if (event.getPointerCount() == 2) {
isMultiTouch = true;
point1_old_x = point1_new_x;
point1_old_y = point1_new_y;
point2_old_x = point2_new_x;
point2_old_y = point2_new_y;
}
break;
case MotionEvent.ACTION_POINTER_DOWN:
// 雙點(diǎn)操作 按下
if (event.getPointerCount() == 2) {
isMultiTouch = true;
point1_old_x = event.getX(0);
point1_old_y = event.getY(0);
point2_old_x = event.getX(1);
point2_old_y = event.getY(1);
distance_old = (float) Math
.sqrt(((point1_old_x - point2_old_x)
* (point1_old_x - point2_old_x) + (point1_old_y - point2_old_y)
* (point1_old_y - point2_old_y)));
}
break;
case MotionEvent.ACTION_MOVE:
// 雙點(diǎn)操作 移動(dòng)
if (event.getPointerCount() == 2) {
isMultiTouch = true;
point1_new_x = event.getX(0);
point1_new_y = event.getY(0);
point2_new_x = event.getX(1);
point2_new_y = event.getY(1);
pinch();
} else {
// 單點(diǎn)移動(dòng) 移動(dòng)
if (event.getPointerCount() == 1) {
if (!isMultiTouch) {
point_new_x = event.getX();
point_new_y = event.getY();
matrix.postTranslate((point_new_x - point_old_x),
(point_new_y - point_old_y));
point_old_x = point_new_x;
point_old_y = point_new_y;
invalidate();
}
}
}
break;
}
return true;
}
// 縮放圖片方法
private void pinch() {
distance_new = (float) Math.sqrt(((point1_new_x - point2_new_x)
* (point1_new_x - point2_new_x) + (point1_new_y - point2_new_y)
* (point1_new_y - point2_new_y)));
matrix.postScale((distance_new / distance_old),
(distance_new / distance_old), this.getWidth() / 2,
this.getTop() / 2);
invalidate();
distance_old = distance_new;
}
/**
* 設(shè)置Bitmap
*
* @param bitmap
*/
public void setImage(Bitmap bitmap) {
this.bitmap = bitmap;
//獲取控件自身起始點(diǎn)
myLocationStart = new int[2];
getLocationOnScreen(myLocationStart);
//獲取控件自身終止點(diǎn)
myLocationEnd = new int[2];
myLocationEnd[0] = getWidth() + myLocationStart[0];
myLocationEnd[1] = getHeight() + myLocationStart[1];
//計(jì)算控件自身中點(diǎn)
myLocationMid = new int[2];
myLocationMid[0] = (myLocationStart[0] + myLocationEnd[0]) / 2;
myLocationMid[1] = (myLocationStart[1] + myLocationEnd[1]) / 2 - myLocationStart[1];
//設(shè)置中間預(yù)覽框邊框色
rectPaint = new Paint();
rectPaint.setColor(Color.WHITE);
rectPaint.setStrokeWidth(2);
rectBgPaint = new Paint();
rectBgPaint.setColor(getResources().getColor(R.color.photo_adjust_for_avator_bg));
//計(jì)算中間預(yù)覽邊框位置
previewEdge = new int[4];
previewEdge[0] = (myLocationMid[0] - myLocationStart[0]) / 8;
previewEdge[1] = myLocationEnd[0] - previewEdge[0];
previewEdge[2] = myLocationMid[1] - ((previewEdge[1] - previewEdge[0]) / 2);
previewEdge[3] = myLocationMid[1] + ((previewEdge[1] - previewEdge[0]) / 2);
//計(jì)算Bitmap起點(diǎn)
bitmapLocXStart = myLocationMid[0] - bitmap.getWidth() / 2;
bitmapLocYStart = myLocationMid[1] - bitmap.getHeight() / 2;
bitmapLocXEnd = bitmapLocXStart + bitmap.getWidth();
bitmapLocYEnd = bitmapLocYStart - bitmap.getHeight();
//調(diào)整Bitmap位置
matrix.postTranslate(bitmapLocXStart, bitmapLocYStart);
PhotoChooseForAvatorImageView.this.invalidate();
}
/**
* 截圖并返回Bitmap對(duì)象
*/
public Bitmap getAdjustedBitmap(Activity activity) {
View view = activity.getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache();
bitmap = view.getDrawingCache();
matrix = new Matrix();
matrix.postScale((CommonSettings.AVATOR_SIZE * 1.0f) / (previewEdge[1] - previewEdge[0]), (CommonSettings.AVATOR_SIZE * 1.0f) / (previewEdge[1] - previewEdge[0]));
return Bitmap.createBitmap(bitmap, previewEdge[0] - 2, previewEdge[2] + myLocationStart[1] - 2, previewEdge[1] - previewEdge[0], previewEdge[1] - previewEdge[0], matrix, false);
}
/**
* 重置Bitmap（回收內(nèi)存）
*/
public void resetBitmap() {
bitmap.recycle();
bitmap = null;
}
}
