如何使视图透明/仅显示绘图在Android Studio中？

huangapple
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英文:

How to make your view transparent / display only the drawing in Android Studio?

问题

我有一个名为DrawView的类，它继承自View，并位于一个TableLayout的上方。我使用这个类来使用drawLine()方法绘制一条简单的线。我的TableLayout被覆盖，因为我的DrawView类位于其上方。我如何防止这种情况发生？我的线条需要位于TableLayout的上方，但该线条并未使用整个画布，所以我认为将背景设置为透明会解决问题，但事实并非如此。

  1. import android.content.Context;
  2. import android.graphics.Canvas;
  3. import android.graphics.Color;
  4. import android.graphics.Paint;
  5. import android.util.AttributeSet;
  6. import android.view.View;
  8. public class DrawView extends View {
  9.     // ... (代码省略，与上方内容相同)
  10. }

这个视图在调用下面的方法之前也是不可见的：

  1. public void displayResult(int result) {
  2.     // TODO: 修复 DrawView 覆盖了 TableLayout 的问题
  3.     DrawView drawView = new DrawView(this);
  4.     //drawView.setBackgroundColor(Color.TRANSPARENT);
  5.     drawView.setVisibility(View.VISIBLE);
  6.     /*...*/
  7. }

但它仍然会覆盖我的TableLayout。

如果DrawView位于TableLayout的下方，我的布局如下所示，可以猜到不会显示任何线条：

如何使视图透明/仅显示绘图在Android Studio中？

如果DrawView位于TableLayout的上方，我的布局如下所示，这样我就得到了一个带有白色背景的线条，完全覆盖了我的TableLayout：

如何使视图透明/仅显示绘图在Android Studio中？

我如何确保只绘制线条，而没有线条的白色背景？

英文:

I have a class named DrawView which extends View and is on top of a TableLayout. I'm using this class to draw 1 simple line using the drawLine() method. My TableLayout is being overdrawn because my DrawView class is on top of it. How can I prevent this? My line needs to be on top of the TableLayout, said line isn't using the whole canvas, so I thought setting the background to transparent would fix it, which isn't the case.

  1. import android.content.Context;
  2. import android.graphics.Canvas;
  3. import android.graphics.Color;
  4. import android.graphics.Paint;
  5. import android.util.AttributeSet;
  6. import android.view.View;
  8. public class DrawView extends View {
  9.     private final Paint paint = new Paint();
  10.     private static int orientation;
  11.     private static int pos;
  12.     public static final int HORIZONTAL = 1;
  13.     public static final int VERTICAL = 2;
  14.     public static final int DIAGONAL = 3;
  15.     public static final int TOP_LEFT = 4;
  16.     public static final int TOP_RIGHT = 5;
  18.     private void init() {
  19.         paint.setColor(Color.BLACK);
  20.         paint.setStrokeWidth(25f);
  21.         paint.setAntiAlias(true);
  22.     }
  24.     public DrawView(Context context) {
  25.         super(context);
  26.         init();
  27.     }
  29.     public DrawView(Context context, AttributeSet attrs) {
  30.         super(context, attrs);
  31.         init();
  32.     }
  34.     public DrawView(Context context, AttributeSet attrs, int defStyle) {
  35.         super(context, attrs, defStyle);
  36.         init();
  37.     }
  39.     public static void setOrientation(int newOrientation) {
  40.         orientation = newOrientation;
  41.     }
  43.     public static void setPosition(int newPosition) {
  44.         pos = newPosition;
  45.     }
  47.     @Override
  48.     public void onDraw(Canvas canvas) {
  49.         final int INDENT = 147;
  50.         canvas.drawColor(Color.TRANSPARENT);
  51.         switch (orientation) {
  52.             case HORIZONTAL:
  53.                 switch (pos) {
  54.                     case 0:
  55.                         canvas.drawLine(10, INDENT, getWidth() - 10, INDENT, paint);
  56.                         break;
  57.                     case 1:
  58.                         canvas.drawLine(10, INDENT * 3, getWidth() - 10, INDENT * 3, paint);
  59.                         break;
  60.                     case 2:
  61.                         canvas.drawLine(10, INDENT * 5, getWidth() - 10, INDENT * 5, paint);
  62.                         break;
  63.                 }
  64.                 break;
  65.             case VERTICAL:
  66.                 switch (pos) {
  67.                     case 0:
  68.                         canvas.drawLine(INDENT, 10, INDENT, getHeight() - 10, paint);
  69.                         break;
  70.                     case 1:
  71.                         canvas.drawLine(INDENT * 3, 10, INDENT * 3, getHeight() - 10, paint);
  72.                         break;
  73.                     case 2:
  74.                         canvas.drawLine(INDENT * 5, 10, INDENT * 5, getHeight() - 10, paint);
  75.                         break;
  76.                 }
  77.                 break;
  78.             case DIAGONAL:
  79.                 if (pos == TOP_LEFT) {
  80.                     canvas.drawLine(10, 10, getWidth() - 10, getHeight() - 10, paint);
  81.                 } else if (pos == TOP_RIGHT) {
  82.                     canvas.drawLine(10, getHeight() - 10, getWidth() - 10, 10, paint);
  83.                 }
  84.                 break;
  85.         }
  86.     }
  88. }

This view is also invisible, until I call this method:

  1. public void displayResult(int result) {
  2.         // TODO: Fix board being overdrawn by DrawView
  3.         DrawView drawView = new DrawView(this);
  4.         //drawView.setBackgroundColor(Color.TRANSPARENT);
  5.         drawView.setVisibility(View.VISIBLE);
  6.         /*...*/
  7.     }

But it still overdraws my TableLayout.
This is how my layout looks if the DrawView is under the TableLayout, as one can guess no line will displayed:

如何使视图透明/仅显示绘图在Android Studio中？

And this is how my layout looks if the DrawView is above the TableLayout, this way I get a line with a white background which completely overdraws my TableLayout:

如何使视图透明/仅显示绘图在Android Studio中？

How can I make sure only the line is drawn without the white background of it?

答案1

得分: 1

对不起，您的要求是只返回翻译好的内容，所以我将仅翻译您提供的文本：

出于我的愧疚，布局的背景，其中包含我的视图（DrawView），被设置为白色。因此，我的视图也有一个白色的画布，从而覆盖了我的 TableLayout。

虽然这可能是一个令人失望的答案，但它可能会帮助将来遇到类似问题的人。

请检查您布局的背景。

英文:

To my shame, the background of the layout, in which my view (DrawView) is, was set to white. Therefore my view also had a white canvas, thus overdrawing my TableLayout.

While this might be an underwhelming answer, it might help someone who comes along this in the future.

Check your layout's background.

huangapple
  • 本文由 发表于 2020年10月2日 17:38:39
  • 转载请务必保留本文链接：https://go.coder-hub.com/64169385.html
  • android
  • android-view
  • java
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