Issue #932: new api: StyledText.setFixedLineMetrics

To be implemented in next commits

Signed-off-by: Alexandr Miloslavskiy <[email protected]>

Author: SyntevoAlex

bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/StyledText.java

@@ -8751,6 +8751,15 @@ private boolean hasMultipleCarets() {
 	return carets != null && carets.length > 1;
 }
 
+/**
+ * See {@link TextLayout#setFixedLineMetrics}
+ *
+ * @since 3.125
+ */
+public void setFixedLineMetrics(FontMetrics metrics) {
+	renderer.setFixedLineMetrics (metrics);
+}
+
 /**
  * Sets a new font to render text with.
  * <p>

bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/StyledTextRenderer.java

@@ -36,6 +36,9 @@ class StyledTextRenderer {
 	StyledTextLineSpacingProvider lineSpacingProvider;
 	boolean lineSpacingComputing;
 
+	/* Custom line metrics */
+	private FontMetrics fixedLineMetrics;
+
 	/* Font info */
 	Font regularFont, boldFont, italicFont, boldItalicFont;
 	int tabWidth;
@@ -1193,6 +1196,7 @@ TextLayout getTextLayout(int lineIndex, int orientation, int width, int lineSpac
 	layout.setFont(regularFont);
 	layout.setAscent(ascent);
 	layout.setDescent(descent);
+	layout.setFixedLineMetrics(fixedLineMetrics);
 	layout.setText(line);
 	layout.setOrientation(orientation);
 	layout.setSegments(segments);
@@ -1378,6 +1382,16 @@ void setContent(StyledTextContent content) {
 	maxWidthLineIndex = -1;
 	reset(0, lineCount);
 }
+
+/**
+ * See {@link TextLayout#setFixedLineMetrics}
+ *
+ * @since 3.125
+ */
+public void setFixedLineMetrics(FontMetrics metrics) {
+	fixedLineMetrics = metrics;
+}
+
 void setFont(Font font, int tabs) {
 	TextLayout layout = new TextLayout(device);
 	layout.setFont(regularFont);

bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/graphics/TextLayout.java

@@ -1768,6 +1768,40 @@ public void setDescent (int descent) {
 	}
 }
 
+/**
+ * Forces line heights in receiver to obey provided value. This is
+ * useful with texts that contain glyphs from different scripts,
+ * such as mixing latin glyphs with hieroglyphs or emojis.
+ * <p>
+ * Text lines with different metrics will be forced to fit. This means
+ * painting text in such a way that its baseline is where specified by
+ * given 'metrics'. This can sometimes introduce small visual artifacs,
+ * such as taller lines overpainting or being clipped by content above
+ * and below.
+ * </p>
+ * The possible ways to set FontMetrics include:
+ * <ul>
+ * <li>Obtaining 'FontMetrics' via {@link GC#getFontMetrics}. Note that
+ * this will only obtain metrics for currently selected font and will not
+ * account for font fallbacks (for example, with a latin font selected,
+ * painting hieroglyphs usually involves a fallback font).</li>
+ * <li>Obtaining 'FontMetrics' via a temporary 'TextLayout'. This would
+ * involve setting a desired text sample to 'TextLayout', then measuring
+ * it with {@link org.eclipse.swt.graphics.TextLayout#getLineMetrics(int)}. This approach will also
+ * take fallback fonts into account.</li>
+ * </ul>
+ *
+ * NOTE: Does not currently support (as in, undefined behavior) multi-line
+ * layouts, including those caused by word wrapping. StyledText uses one
+ * TextLayout per line and is only affected by word wrap restriction.
+ *
+ * @since 3.125
+ */
+public void setFixedLineMetrics (FontMetrics metrics) {
+	if (metrics == null) return;
+	SWT.error(SWT.ERROR_NOT_IMPLEMENTED);
+}
+
 /**
  * Sets the default font which will be used by the receiver
  * to draw and measure text. If the

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/graphics/TextLayout.java

@@ -1798,6 +1798,40 @@ public void setDescent (int descent) {
 	this.descentInPoints = descent;
 }
 
+/**
+ * Forces line heights in receiver to obey provided value. This is
+ * useful with texts that contain glyphs from different scripts,
+ * such as mixing latin glyphs with hieroglyphs or emojis.
+ * <p>
+ * Text lines with different metrics will be forced to fit. This means
+ * painting text in such a way that its baseline is where specified by
+ * given 'metrics'. This can sometimes introduce small visual artifacs,
+ * such as taller lines overpainting or being clipped by content above
+ * and below.
+ * </p>
+ * The possible ways to set FontMetrics include:
+ * <ul>
+ * <li>Obtaining 'FontMetrics' via {@link GC#getFontMetrics}. Note that
+ * this will only obtain metrics for currently selected font and will not
+ * account for font fallbacks (for example, with a latin font selected,
+ * painting hieroglyphs usually involves a fallback font).</li>
+ * <li>Obtaining 'FontMetrics' via a temporary 'TextLayout'. This would
+ * involve setting a desired text sample to 'TextLayout', then measuring
+ * it with {@link org.eclipse.swt.graphics.TextLayout#getLineMetrics(int)}. This approach will also
+ * take fallback fonts into account.</li>
+ * </ul>
+ *
+ * NOTE: Does not currently support (as in, undefined behavior) multi-line
+ * layouts, including those caused by word wrapping. StyledText uses one
+ * TextLayout per line and is only affected by word wrap restriction.
+ *
+ * @since 3.125
+ */
+public void setFixedLineMetrics (FontMetrics metrics) {
+	if (metrics == null) return;
+	SWT.error(SWT.ERROR_NOT_IMPLEMENTED);
+}
+
 /**
  * Sets the default font which will be used by the receiver
  * to draw and measure text. If the

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/graphics/TextLayout.java

@@ -3078,6 +3078,40 @@ public void setDescent (int descent) {
 	this.descentInPixels = descent;
 }
 
+/**
+ * Forces line heights in receiver to obey provided value. This is
+ * useful with texts that contain glyphs from different scripts,
+ * such as mixing latin glyphs with hieroglyphs or emojis.
+ * <p>
+ * Text lines with different metrics will be forced to fit. This means
+ * painting text in such a way that its baseline is where specified by
+ * given 'metrics'. This can sometimes introduce small visual artifacs,
+ * such as taller lines overpainting or being clipped by content above
+ * and below.
+ * </p>
+ * The possible ways to set FontMetrics include:
+ * <ul>
+ * <li>Obtaining 'FontMetrics' via {@link GC#getFontMetrics}. Note that
+ * this will only obtain metrics for currently selected font and will not
+ * account for font fallbacks (for example, with a latin font selected,
+ * painting hieroglyphs usually involves a fallback font).</li>
+ * <li>Obtaining 'FontMetrics' via a temporary 'TextLayout'. This would
+ * involve setting a desired text sample to 'TextLayout', then measuring
+ * it with {@link TextLayout#getLineMetrics(int)}. This approach will also
+ * take fallback fonts into account.</li>
+ * </ul>
+ *
+ * NOTE: Does not currently support (as in, undefined behavior) multi-line
+ * layouts, including those caused by word wrapping. StyledText uses one
+ * TextLayout per line and is only affected by word wrap restriction.
+ *
+ * @since 3.125
+ */
+public void setFixedLineMetrics (FontMetrics metrics) {
+	if (metrics == null) return;
+	SWT.error(SWT.ERROR_NOT_IMPLEMENTED);
+}
+
 /**
  * Sets the default font which will be used by the receiver
  * to draw and measure text. If the