Home >Java >javaTutorial >How to Achieve Transparent Corners in a Rounded Rectangle Border?
Problem Statement:
The query revolves around TextBubbleBorder, a custom border designed for text areas. However, when the border is used to create a rounded rectangle (by setting the pointer size to zero), the corners outside the rectangle remained opaque, displaying the default panel color instead of the desired transparency.
Solution Overview:
The key to achieving transparency in the border corners lies in painting the background color of the parent component over the areas outside the rounded rectangle. This involves:
Modified Code:
The following modified paintBorder method within the TextBubbleBorder class incorporates the above steps:
@Override public void paintBorder( Component c, Graphics g, int x, int y, int width, int height) { Graphics2D g2 = (Graphics2D) g; // ... (unchanged code) // Paint the BG color of the parent, everywhere outside the clip // of the text bubble. Component parent = c.getParent(); if (parent!=null) { Color bg = parent.getBackground(); Rectangle rect = new Rectangle(0,0,width, height); Area borderRegion = new Area(rect); borderRegion.subtract(area); g2.setClip(borderRegion); g2.setColor(bg); g2.fillRect(0, 0, width, height); g2.setClip(null); } // ... (unchanged code) }
Result:
This modification effectively draws the parent background in the areas outside the rounded corners, producing the desired transparent border. You can now create a rounded rectangle with a transparent border that seamlessly integrates with its parent component.
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