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我完成了ImageView上的绘图文本，并将最终图像保存在SD卡中。我的问题是，当我触摸屏幕来绘制文本时，ImageView中的图像正在消失。Android：用手指触摸在ImageView上绘制文本
代码
import java.io.File;
import java.io.FileOutputStream;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.os.StrictMode;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
public class DrawTextOnImgActivity extends Activity {
private Button btn_save, btn_resume;
private ImageView iv_canvas;
private Bitmap baseBitmap;
private Canvas canvas;
private Paint paint;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_draw_text_on_img);
// The initialization of a brush, brush width is 5, color is red
paint = new Paint();
paint.setStrokeWidth(5);
paint.setColor(Color.RED);
iv_canvas = (ImageView) findViewById(R.id.imageView1);
btn_save = (Button) findViewById(R.id.btn_save);
btn_resume = (Button) findViewById(R.id.btn_resume);
btn_save.setOnClickListener(click);
btn_resume.setOnClickListener(click);
iv_canvas.setOnTouchListener(touch);
}
private View.OnTouchListener touch = new OnTouchListener() {
// Coordinate definition finger touch
float startX;
float startY;
@SuppressLint("ClickableViewAccessibility")
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
// Press the user action
case MotionEvent.ACTION_DOWN:
// The first drawing initializes the memory image, specify the background is white
if (baseBitmap == null) {
baseBitmap = Bitmap.createBitmap(iv_canvas.getWidth(),
iv_canvas.getHeight(), Bitmap.Config.ARGB_8888);
canvas = new Canvas(baseBitmap);
canvas.drawColor(Color.WHITE);
}
// Recording began to touch point coordinate
startX = event.getX();
startY = event.getY();
break;
// The user's finger on the screen of mobile action
case MotionEvent.ACTION_MOVE:
// Record the coordinates of the mobile point
float stopX = event.getX();
float stopY = event.getY();
//According to the coordinates of the two points, drawing lines
canvas.drawLine(startX, startY, stopX, stopY, paint);
// Update start point
startX = event.getX();
startY = event.getY();
// The pictures to the ImageView
iv_canvas.setImageBitmap(baseBitmap);
break;
case MotionEvent.ACTION_UP:
break;
default:
break;
}
return true;
}
};
private View.OnClickListener click = new OnClickListener() {
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_save:
saveBitmap();
break;
case R.id.btn_resume:
resumeCanvas();
break;
default:
break;
}
}
};
/**
* Save the image to the SD card.
*/
protected void saveBitmap() {
try {
// Save the image to the SD card.
File folder = new File(Environment.getExternalStorageDirectory() + "/DrawTextOnImg");
if (!folder.exists()) {
folder.mkdir();
}
File file = new File(Environment.getExternalStorageDirectory()+"/DrawTextOnImg/tempImg.png");
FileOutputStream stream = new FileOutputStream(file);
baseBitmap.compress(CompressFormat.PNG, 100, stream);
Toast.makeText(DrawTextOnImgActivity.this, "Save the picture of success", Toast.LENGTH_SHORT).show();
// Android equipment Gallery application will only at boot time scanning system folder
// The simulation of a media loading broadcast, for the preservation of images can be viewed in Gallery
Intent intent = new Intent();
intent.setAction(Intent.ACTION_MEDIA_MOUNTED);
intent.setData(Uri.fromFile(Environment.getExternalStorageDirectory()));
sendBroadcast(intent);
} catch (Exception e) {
Toast.makeText(DrawTextOnImgActivity.this, "Save failed", Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
}
/**
* Clear the drawing board
*/
protected void resumeCanvas() {
// Manually clear the drawing board, to create a drawing board
if (baseBitmap != null) {
baseBitmap = Bitmap.createBitmap(iv_canvas.getWidth(), iv_canvas.getHeight(), Bitmap.Config.ARGB_8888);
canvas = new Canvas(baseBitmap);
canvas.drawColor(Color.WHITE);
iv_canvas.setImageBitmap(baseBitmap);
Toast.makeText(DrawTextOnImgActivity.this, "Clear the drawing board, can be re started drawing", Toast.LENGTH_SHORT).show();
}
}
}
清单
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<protected-broadcast android:name="android.intent.action.MEDIA_MOUNTED" />
通过使用此代码我写上的ImageView，但在ImageView的形象正在消失的文字。所以，请帮我写下ImageView的图像文字
什么时候图像消失？ ACTION_MOVE，ACTION_DOWN或ACTION_UP？ – cjds
@cjds：图像在所有上述情况下消失 – Bahu