API Reference: TextLine

TextLine represents a single line of shaped text. It is typically created by the Shaper and provides metric information and hit-testing capabilities essential for building text editors or interactive labels.

Creation

// Shape a single line of text
TextLine line = TextLine.make("Hello World", font);

Metrics

• getAscent(): Distance from baseline to top of highest glyph (negative).
• getDescent(): Distance from baseline to bottom of lowest glyph (positive).
• getCapHeight(): Height of capital letters.
• getXHeight(): Height of lowercase 'x'.
• getWidth(): Total advance width of the line.
• getHeight(): Total height (descent - ascent).

Hit Testing (Interaction)

TextLine provides methods to map between pixel coordinates and character offsets.

// 1. Get Offset from Coordinate (Clicking)
float x = mouseEvent.getX();
int offset = line.getOffsetAtCoord(x); // Returns UTF-16 character index
// 'offset' will be closest to the mouse cursor

// 2. Get Coordinate from Offset (Cursor Placement)
float cursorX = line.getCoordAtOffset(offset);
// Draw a cursor at (cursorX, baseline)

• getOffsetAtCoord(x): Closest character offset.
• getLeftOffsetAtCoord(x): Character offset strictly to the left.
• getCoordAtOffset(offset): Pixel X-coordinate for a given character index.

Rendering

// You can draw the line directly
canvas.drawTextLine(line, x, y, paint);

// Or extract the TextBlob for more manual control
try (TextBlob blob = line.getTextBlob()) {
    canvas.drawTextBlob(blob, x, y, paint);
}

Lifecycle

TextLine implements Managed. Always close it when you are done to free native resources.

try (TextLine line = TextLine.make(text, font)) {
    // ... use line ...
}