一、概述
app中有需求需要将View转化为图片并保存到本地,这里分两种情况:
1.View本身已经显示在界面上
2.View还没有添加到界面上或者没有显示(绘制)过
二、实现方法
对于上述的第一种情况我使用下面代码即可:
private void viewSaveToImage(View view) {
view.setDrawingCacheEnabled(true);
view.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
view.setDrawingCacheBackgroundColor(Color.WHITE);
// 把一个View转换成图片
Bitmap cachebmp = loadBitmapFromView(view);
FileOutputStream fos;
String imagePath = "";
try {
// 判断手机设备是否有SD卡
boolean isHasSDCard = Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED);
if (isHasSDCard) {
// SD卡根目录
File sdRoot = Environment.getExternalStorageDirectory();
File file = new File(sdRoot, Calendar.getInstance().getTimeInMillis()+".png");
fos = new FileOutputStream(file);
imagePath = file.getAbsolutePath();
} else
throw new Exception("创建文件失败!");
cachebmp.compress(Bitmap.CompressFormat.PNG, 90, fos);
fos.flush();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
LogUtil.e("imagePath="+imagePath);
view.destroyDrawingCache();
}
private Bitmap loadBitmapFromView(View v) {
int w = v.getWidth();
int h = v.getHeight();
Bitmap bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(bmp);
c.drawColor(Color.WHITE);
/** 如果不设置canvas画布为白色,则生成透明 */
v.layout(0, 0, w, h);
v.draw(c);
return bmp;
}
也可以按下面做:
public static Bitmap getBitmapByView(ScrollView scrollView) {
int h = 0;
Bitmap bitmap = null;
for (int i = 0; i < scrollView.getChildCount(); i++) {
h += scrollView.getChildAt(i).getHeight();
}
bitmap = Bitmap.createBitmap(scrollView.getWidth(), h,
Bitmap.Config.RGB_565);
final Canvas canvas = new Canvas(bitmap);
scrollView.draw(canvas);
return bitmap;
}
满足layout生成bitmap,然后bitmap可以再生成图片
public static void savePhotoToSDCard(Bitmap photoBitmap, String path, String photoName) {
if (checkSDCardAvailable()) {
File dir = new File(path);
if (!dir.exists()) {
dir.mkdirs();
}
File photoFile = new File(path, photoName + ".png");
FileOutputStream fileOutputStream = null;
try {
fileOutputStream = new FileOutputStream(photoFile);
if (photoBitmap != null) {
if (photoBitmap.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream)) {
fileOutputStream.flush();
}
}
} catch (FileNotFoundException e) {
photoFile.delete();
e.printStackTrace();
} catch (IOException e) {
photoFile.delete();
e.printStackTrace();
} finally {
try {
fileOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
检查是否有SD卡
public static boolean checkSDCardAvailable() {
return android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);
}
用例:
Bitmap bitmap = getBitmapByView(contentLly);//contentLly是布局文件
ImageUtils.savePhotoToSDCard(bitmap, "/sdcard/test", "test");
如果是第二种,还这样使用的话,就会报错了,因为View在添加到容器中之前并没有得到实际的大小,所以首先需要指定View的大小:
DisplayMetrics metric = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metric);
int width = metric.widthPixels; // 屏幕宽度(像素)
int height = metric.heightPixels; // 屏幕高度(像素)
View mingpianView = LayoutInflater.from(this).inflate(R.layout.view_team_mingpian, null, false);
layoutView(mingpianView, width, height);
//然后View和其内部的子View都具有了实际大小,也就是完成了布局,相当与添加到了界面上。接着就可以创建位图并在上面绘制了:
private void layoutView(View v, int width, int height) {
// 指定整个View的大小 参数是左上角 和右下角的坐标
v.layout(0, 0, width, height);
int measuredWidth = View.MeasureSpec.makeMeasureSpec(width, View.MeasureSpec.EXACTLY);
int measuredHeight = View.MeasureSpec.makeMeasureSpec(height, View.MeasureSpec.AT_MOST);
/** 当然,measure完后,并不会实际改变View的尺寸,需要调用View.layout方法去进行布局。
* 按示例调用layout函数后,View的大小将会变成你想要设置成的大小。
*/
v.measure(measuredWidth, measuredHeight);
v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredHeight());
}
在int measuredHeight = View.MeasureSpec.makeMeasureSpec(height, View.MeasureSpec.AT_MOST);
这里我有点不懂后面函数的取值。在自定义view里onMeasure()里有根据MeasureSpec.getMode()的类型来准确得到设置view的长宽
.makeMeasureSpec(height, View.MeasureSpec.AT_MOST);却貌似取了 自适应和前一个int参数的最小值。
后面我发现有可能合成出超出屏幕的长图,就直接吧前一个int参数赋值成一个很大的数字。。。
MainActivity
public class MainActivity extends Activity {
ImageView aaa ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DisplayMetrics metric = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metric);
int width = metric.widthPixels; // 屏幕宽度(像素)
int height = metric.heightPixels; // 屏幕高度(像素)
View view = LayoutInflater.from(this).inflate(R.layout.view_photo, null, false);
layoutView(view, width, height);
final ScrollView tv = (ScrollView) view.findViewById(R.id.textView);
aaa = (ImageView) findViewById(R.id.aaa);
final Runnable runnable = new Runnable() {
@Override
public void run() {
viewSaveToImage(tv);
}
};
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new Handler().post(runnable);
}
});
}
//然后View和其内部的子View都具有了实际大小,也就是完成了布局,相当与添加到了界面上。接着就可以创建位图并在上面绘制了:
private void layoutView(View v, int width, int height) {
// 整个View的大小 参数是左上角 和右下角的坐标
v.layout(0, 0, width, height);
int measuredWidth = View.MeasureSpec.makeMeasureSpec(width, View.MeasureSpec.EXACTLY);
int measuredHeight = View.MeasureSpec.makeMeasureSpec(10000, View.MeasureSpec.AT_MOST);
/** 当然,measure完后,并不会实际改变View的尺寸,需要调用View.layout方法去进行布局。
* 按示例调用layout函数后,View的大小将会变成你想要设置成的大小。
*/
v.measure(measuredWidth, measuredHeight);
v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredHeight());
}
public void viewSaveToImage(View view) {
Log.e("ssh","a");
/**
* View组件显示的内容可以通过cache机制保存为bitmap
* 我们要获取它的cache先要通过setDrawingCacheEnable方法把cache开启,
* 然后再调用getDrawingCache方法就可 以获得view的cache图片了
* 。buildDrawingCache方法可以不用调用,因为调用getDrawingCache方法时,
* 若果 cache没有建立,系统会自动调用buildDrawingCache方法生成cache。
* 若果要更新cache, 必须要调用destoryDrawingCache方法把旧的cache销毁,才能建立新的。
*/
// view.setDrawingCacheEnabled(true);
// view.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
//设置绘制缓存背景颜色
// view.setDrawingCacheBackgroundColor(Color.WHITE);
// 把一个View转换成图片
Bitmap cachebmp = loadBitmapFromView(view);
aaa.setImageBitmap(cachebmp);//直接展示转化的bitmap
//保存在本地 产品还没决定要不要保存在本地
FileOutputStream fos;
try {
// 判断手机设备是否有SD卡
boolean isHasSDCard = Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED);
if (isHasSDCard) {
// SD卡根目录
File sdRoot = Environment.getExternalStorageDirectory();
Log.e("ssh",sdRoot.toString());
File file = new File(sdRoot, "test.png");
fos = new FileOutputStream(file);
} else
throw new Exception("创建文件失败!");
//压缩图片 30 是压缩率,表示压缩70%; 如果不压缩是100,表示压缩率为0
cachebmp.compress(Bitmap.CompressFormat.PNG, 90, fos);
fos.flush();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
view.destroyDrawingCache();
}
private Bitmap loadBitmapFromView(View v) {
int w = v.getWidth();
int h = v.getHeight();
Bitmap bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(bmp);
c.drawColor(Color.WHITE);
/** 如果不设置canvas画布为白色,则生成透明 */
v.layout(0, 0, w, h);
v.draw(c);
return bmp;
}
}
参考:
https://blog.youkuaiyun.com/qq_16247851/article/details/72772370
https://blog.youkuaiyun.com/shallcheek/article/details/46998643
https://blog.youkuaiyun.com/a450479378/article/details/53081814
https://blog.youkuaiyun.com/chenzheng8975/article/details/76206290