Add a text rendering utility class to the Asset Studio library.

Add a text rendering utility class to the Asset Studio library. Also
fix a tiny edge-case bug in image scaling. The text rendering class
allows rendering a String with some options to a BufferedImage, for
input as the sourceImage to a GraphicGenerator.

Change-Id: I8e17e9a25ac2e48fa55e2994706aeb572da54223

2 files changed, 114 insertions, 4 deletions

diff --git a/assetstudio/src/com/android/assetstudiolib/TextRenderUtil.java b/assetstudio/src/com/android/assetstudiolib/TextRenderUtil.java
new file mode 100644
index 0000000..a103701
--- /dev/null
+++ b/assetstudio/src/com/android/assetstudiolib/TextRenderUtil.java
@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.assetstudiolib;
+
+import java.awt.Font;
+import java.awt.Graphics2D;
+import java.awt.font.FontRenderContext;
+import java.awt.font.TextAttribute;
+import java.awt.geom.Rectangle2D;
+import java.awt.image.BufferedImage;
+import java.util.Hashtable;
+import java.util.Map;
+
+/**
+ * A set of utility classes for rendering text to a {@link BufferedImage}, suitable for use as a
+ * source image to {@link GraphicGenerator} objects.
+ */
+public class TextRenderUtil {
+    /**
+     * Renders the given string with the provided {@link Options} to a {@link BufferedImage}.
+     *
+     * @param text    The text to render.
+     * @param options The optional parameters for rendering the text.
+     * @return An image, suitable for use as an input to a {@link GraphicGenerator}.
+     */
+    public static BufferedImage renderTextImage(String text, Options options) {
+        if (options == null) {
+            options = new Options();
+        }
+
+        BufferedImage tempImage = Util.newArgbBufferedImage(1, 1);
+        if (text == null || text.equals("")) {
+            return tempImage;
+        }
+
+        Graphics2D tempG = (Graphics2D) tempImage.getGraphics();
+
+        Font font = options.font;
+        if (font == null) {
+            font = new Font(options.fontName, options.fontStyle, options.fontSize);
+            // Map<TextAttribute, Object> map = new Hashtable<TextAttribute, Object>();
+            // map.put(TextAttribute.TRACKING, 0.3);
+            // font = font.deriveFont(map);
+        }
+
+        FontRenderContext frc = tempG.getFontRenderContext();
+
+        Rectangle2D bounds = font.getStringBounds(text, frc);
+
+        BufferedImage image = Util.newArgbBufferedImage(
+                Math.max(1, (int) bounds.getWidth()), Math.max(1, (int) bounds.getHeight()));
+        Graphics2D g = (Graphics2D) image.getGraphics();
+        g.setFont(font);
+        g.drawString(text, 0, (float) -bounds.getY());
+
+        return image;
+    }
+
+    /**
+     * The parameters for text rendering. There are no required values so a <code>new
+     * Options()</code> object is considered valid.
+     */
+    public static class Options {
+        // We use a large default font size to reduce the need to scale generated images up.
+        // TODO: Instead, a graphic generator should use a different source image for each density.
+        private static final int DEFAULT_FONT_SIZE = 512;
+
+        /**
+         * The optional {@link Font} to use. If null, a {@link Font} object will be generated using
+         * the other options.
+         */
+        public Font font = null;
+
+        /**
+         * The optional font name. Defaults to {@link Font#SERIF}.
+         *
+         * @see Font#Font(String, int, int)
+         */
+        public String fontName = Font.SERIF;
+
+        /**
+         * The optional font styling (bold and/or italic). Defaults to no styling.
+         *
+         * @see Font#Font(String, int, int)
+         */
+        public int fontStyle = 0;
+
+        /**
+         * The optional font size, in points. Defaults to a very large font size, to prevent
+         * up-scaling rendered text.
+         *
+         * @see Font#Font(String, int, int)
+         */
+        public int fontSize = DEFAULT_FONT_SIZE;
+    }
+}
diff --git a/assetstudio/src/com/android/assetstudiolib/Util.java b/assetstudio/src/com/android/assetstudiolib/Util.java
index 82299a4..1a6b00e 100644
--- a/assetstudio/src/com/android/assetstudiolib/Util.java
+++ b/assetstudio/src/com/android/assetstudiolib/Util.java
@@ -325,8 +325,8 @@ public class Util {
         final int srcWidth = source.getWidth();
         final int srcHeight = source.getHeight();
         if (srcWidth * 1.0 / srcHeight > dstRect.width * 1.0 / dstRect.height) {
-            final int scaledWidth = dstRect.width;
-            final int scaledHeight = dstRect.width * srcHeight / srcWidth;
+            final int scaledWidth = Math.max(1, dstRect.width);
+            final int scaledHeight = Math.max(1, dstRect.width * srcHeight / srcWidth);
             Image scaledImage = scaledImage(source, scaledWidth, scaledHeight);
             g.drawImage(scaledImage,
                     dstRect.x,
@@ -339,8 +339,8 @@ public class Util {
                     0 + scaledHeight,
                     null);
         } else {
-            final int scaledWidth = dstRect.height * srcWidth / srcHeight;
-            final int scaledHeight = dstRect.height;
+            final int scaledWidth = Math.max(1, dstRect.height * srcWidth / srcHeight);
+            final int scaledHeight = Math.max(1, dstRect.height);
             Image scaledImage = scaledImage(source, scaledWidth, scaledHeight);
             g.drawImage(scaledImage,
                     dstRect.x + (dstRect.width - scaledWidth) / 2,