Android - 如何绘制描边位图？

发布于 2025-01-13 04:20:06 字数 172 浏览 6 评论 0原文

我有一个如图所示的位图。我想使用 Canvas 为其添加边框。谁能帮助我吗？

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[浮城] 2025-01-20 04:20:06

您可以使用 Paint.STYLE.STROKE 绘制边框。您需要进行两次单独的绘图调用。

paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.parseColor("#BAB399")); // set fill color
canvas.drawCircle(sbmp.getWidth() / 2+0.7f, sbmp.getHeight() / 2+0.7f,
    sbmp.getWidth() / 2+0.1f, paint);

paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(10); // set stroke width
paint.setColor(Color.parseColor("#ffffff")); // set stroke color
canvas.drawCircle(sbmp.getWidth() / 2+0.7f, sbmp.getHeight() / 2+0.7f,
    sbmp.getWidth() / 2+0.1f, paint);

You can draw a border using Paint.STYLE.STROKE. You need to do two separate calls to draw.

paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.parseColor("#BAB399")); // set fill color
canvas.drawCircle(sbmp.getWidth() / 2+0.7f, sbmp.getHeight() / 2+0.7f,
    sbmp.getWidth() / 2+0.1f, paint);

paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(10); // set stroke width
paint.setColor(Color.parseColor("#ffffff")); // set stroke color
canvas.drawCircle(sbmp.getWidth() / 2+0.7f, sbmp.getHeight() / 2+0.7f,
    sbmp.getWidth() / 2+0.1f, paint);

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玻璃人 2025-01-20 04:20:06

如果图像具有透明背景（png 文件）并且描边大小不太大，则可以仅绘制位图并对其应用 4 次颜色叠加 - 左、上、右和下。

final float stroke = 20F; //stroke size in pixels.
//Load target image as bitmap.
BitmapFactory.Options options = new BitmapFactory.Options();
options.inMutable = true;
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.shap, options);
//A new, clear bitmap with same size.
Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(newBitmap);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
//Overlay target bitmap with black color.
PorterDuffColorFilter filter = new PorterDuffColorFilter(Color.BLACK, PorterDuff.Mode.SRC_IN);
paint.setColorFilter(filter);
//Draw target bitmap over new bitmap.
canvas.drawBitmap(bitmap, -stroke, 0F, paint); //left
canvas.drawBitmap(bitmap, 0F, -stroke, paint); //top
canvas.drawBitmap(bitmap, stroke, 0F, paint); //right
canvas.drawBitmap(bitmap, 0F, stroke, paint); //bottom
//Remove overlay.
paint.setColorFilter(null);
//Draw target bitmap.
canvas.drawBitmap(bitmap, 0F, 0F, paint);
//Load new bitmap into ImageView.
ImageView iv = findViewById(R.id.iv);
iv.setImageBitmap(newBitmap);

If the image has a transparent background (png file) and the stroke size is not too large, you can just draw the bitmap with a color overlay applied to it 4 times -- left, top, right and bottom.

final float stroke = 20F; //stroke size in pixels.
//Load target image as bitmap.
BitmapFactory.Options options = new BitmapFactory.Options();
options.inMutable = true;
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.shap, options);
//A new, clear bitmap with same size.
Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(newBitmap);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
//Overlay target bitmap with black color.
PorterDuffColorFilter filter = new PorterDuffColorFilter(Color.BLACK, PorterDuff.Mode.SRC_IN);
paint.setColorFilter(filter);
//Draw target bitmap over new bitmap.
canvas.drawBitmap(bitmap, -stroke, 0F, paint); //left
canvas.drawBitmap(bitmap, 0F, -stroke, paint); //top
canvas.drawBitmap(bitmap, stroke, 0F, paint); //right
canvas.drawBitmap(bitmap, 0F, stroke, paint); //bottom
//Remove overlay.
paint.setColorFilter(null);
//Draw target bitmap.
canvas.drawBitmap(bitmap, 0F, 0F, paint);
//Load new bitmap into ImageView.
ImageView iv = findViewById(R.id.iv);
iv.setImageBitmap(newBitmap);

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