libgui|Font: Rasterizing a line of text onto an image

skyjake · May 18, 2013 · f386b1e · f386b1e
1 parent 99d3aa2
commit f386b1e
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Showing 2 changed files with 36 additions and 0 deletions.
diff --git a/doomsday/libgui/include/de/gui/font.h b/doomsday/libgui/include/de/gui/font.h
@@ -23,8 +23,10 @@
 #include <de/Rule>
 #include <de/Rectangle>
 #include <de/String>
+#include <de/Vector>
 
 #include <QFont>
+#include <QImage>
 
 #include "libgui.h"
 
@@ -55,6 +57,19 @@ class LIBGUI_PUBLIC Font
      */
     Rectanglei measure(String const &textLine) const;
 
+    /**
+     * Rasterizes a line of text onto a 32-bit RGBA image.
+     *
+     * @param textLine    Text to rasterize.
+     * @param foreground  Text foreground color.
+     * @param background  Background color.
+     *
+     * @return
+     */
+    QImage rasterize(String const &textLine,
+                     Vector4ub const &foreground = Vector4ub(255, 255, 255, 255),
+                     Vector4ub const &background = Vector4ub(255, 255, 255, 0)) const;
+
     Rule const &height() const;
     Rule const &ascent() const;
     Rule const &descent() const;

diff --git a/doomsday/libgui/src/font.cpp b/doomsday/libgui/src/font.cpp
@@ -20,6 +20,8 @@
 
 #include <de/ConstantRule>
 #include <QFontMetrics>
+#include <QImage>
+#include <QPainter>
 
 namespace de {
 
@@ -81,6 +83,25 @@ Rectanglei Font::measure(String const &textLine) const
     return Rectanglei::fromQRect(d->metrics->boundingRect(textLine));
 }
 
+QImage Font::rasterize(String const &textLine,
+                       Vector4ub const &foreground,
+                       Vector4ub const &background) const
+{
+    Rectanglei bounds = measure(textLine);
+
+    QImage img(QSize(bounds.width(), bounds.height()), QImage::Format_ARGB32);
+
+    QColor bgColor(background.x, background.y, background.z, background.w);
+    img.fill(bgColor.rgba());
+
+    QPainter painter(&img);
+    painter.setFont(d->font);
+    painter.setPen(QColor(foreground.x, foreground.y, foreground.z, foreground.w));
+    painter.setBrush(bgColor);
+    painter.drawText(0, d->ascentRule->valuei(), textLine);
+    return img;
+}
+
 Rule const &Font::height() const
 {
     return *d->heightRule;