英文:
Modifying bitmap image
问题
我正在处理一个 Android Studio 项目。我正在尝试选择用户在图像上触摸的像素，如图1所示。
我想在用户触摸的像素上添加（X），我该如何通过修改 bitmap 来实现？
这是图像。
图片：链接 宽度：800。
英文:
I'm working with an android studio project. I'm trying to select user touched pixel on an image, as shown Fig 1.
I want to add (X) on a pixel touched by the user, how can I make it by modifying bitmap ?
This is image.
<img src="https://i.stack.imgur.com/8f9df.png" width="800"/>
答案1
得分: 0
如果我正确理解你的问题，你希望在用户每次点击位图时都在上面绘制 X，以下是你需要的代码：
ImageView img;
int clickCount = 0;
Bitmap src;
int colorTarget = Color.BLACK;
@SuppressLint("ClickableViewAccessibility")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
img = findViewById(R.id.img);
img.setOnTouchListener((v, event) -> {
int x = (int) event.getX();
int y = (int) event.getY();
if (event.getAction() == MotionEvent.ACTION_DOWN) {
drawXByPosition(img, src, x, y);
} else if (event.getAction() == MotionEvent.ACTION_UP) {
clickCount++;
if (clickCount % 2 == 0) colorTarget = Color.BLACK;
else colorTarget = Color.WHITE;
}
return true;
});
}
private void drawXByPosition(ImageView iv, Bitmap bm, int x, int y) {
if (x < 0 || y < 0 || x > iv.getWidth() || y > iv.getHeight())
Toast.makeText(getApplicationContext(), "超出 ImageView 范围", Toast.LENGTH_SHORT).show();
else {
int projectedX = (int) ((double) x * ((double) bm.getWidth() / (double) iv.getWidth()));
int projectedY = (int) ((double) y * ((double) bm.getHeight() / (double) iv.getHeight()));
src = drawX(src, "X", 44, colorTarget, projectedX, projectedY);
img.setImageBitmap(src);
}
}
public Bitmap drawX(final Bitmap src,
final String content,
final float textSize,
@ColorInt final int color,
final float x,
final float y) {
Bitmap ret = src.copy(src.getConfig(), true);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
Canvas canvas = new Canvas(ret);
paint.setColor(color);
paint.setTextSize(textSize);
Rect bounds = new Rect();
paint.getTextBounds(content, 0, content.length(), bounds);
canvas.drawText(content, x, y + textSize, paint);
return ret;
}
英文:
If I understand your question correctly, you want to draw X in each time the user click on Bitmap, here's what you need :
ImageView img;
int clickCount = 0;
Bitmap src;
int colorTarget = Color.BLACK;
@SuppressLint("ClickableViewAccessibility")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
img = findViewById(R.id.img);
img.setOnTouchListener((v, event) -> {
int x = (int) event.getX();
int y = (int) event.getY();
if (event.getAction() == MotionEvent.ACTION_DOWN) {
drawXByPosition(img, src, x, y);
} else if (event.getAction() == MotionEvent.ACTION_UP) {
clickCount++;
if (clickCount % 2 == 0) colorTarget = Color.BLACK;
else colorTarget = Color.WHITE;
}
return true;
});
}
private void drawXByPosition(ImageView iv, Bitmap bm, int x, int y) {
if (x < 0 || y < 0 || x > iv.getWidth() || y > iv.getHeight())
Toast.makeText(getApplicationContext(), "Outside of ImageView", Toast.LENGTH_SHORT).show();
else {
int projectedX = (int) ((double) x * ((double) bm.getWidth() / (double) iv.getWidth()));
int projectedY = (int) ((double) y * ((double) bm.getHeight() / (double) iv.getHeight()));
src = drawX(src, "X", 44, colorTarget, projectedX, projectedY);
img.setImageBitmap(src);
}
}
public Bitmap drawX(final Bitmap src,
final String content,
final float textSize,
@ColorInt final int color,
final float x,
final float y) {
Bitmap ret = src.copy(src.getConfig(), true);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
Canvas canvas = new Canvas(ret);
paint.setColor(color);
paint.setTextSize(textSize);
Rect bounds = new Rect();
paint.getTextBounds(content, 0, content.length(), bounds);
canvas.drawText(content, x, y + textSize, paint);
return ret;
}
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