[API] ImFontGlyphRangesBuilder and fonts example

imgui-binding/src/main/java/imgui/ImFontGlyphRangesBuilder.java

@@ -0,0 +1,98 @@
+package imgui;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Helper to build glyph ranges from text/string data. Feed your application strings/characters to it then call buildRanges().
+ * <p>
+ * You can use the ImFontGlyphRangesBuilder helper to create glyph ranges based on text input. For example: for a game where your script is known,
+ * if you can feed your entire script to it and only build the characters the game needs.
+ * <p>
+ * Direct reimplementation of native ImFontGlyphRangesBuilder in java
+ */
+public final class ImFontGlyphRangesBuilder {
+
+    private static final int UNICODE_CODEPOINT_MAX = 0xFFFF;
+
+    // have to use type long because values are unsigned integers
+    private final long[] usedChars = new long[(UNICODE_CODEPOINT_MAX + 1) / 8];
+
+    public ImFontGlyphRangesBuilder() {
+        clear();
+    }
+
+    /**
+     * Adds single character to resulting ranges
+     */
+    public void addChar(final char c) {
+        setBit(c);
+    }
+
+    /**
+     * Adds all characters from the given string to resulting ranges
+     */
+    public void addText(final String text) {
+        for (int i = 0; i < text.length(); i++) {
+            addChar(text.charAt(i));
+        }
+    }
+
+    /**
+     * Copies all given ranges to resulting ranges
+     */
+    public void addRanges(final short[] ranges) {
+        for (int i = 0; i < ranges.length; i += 2) {
+            if (ranges[i] == 0) {
+                break;
+            }
+
+            for (int k = ranges[i]; k <= ranges[i + 1]; k++) {
+                addChar((char) k);
+            }
+        }
+    }
+
+    /**
+     * Builds the final result (ordered ranges with all the unique characters submitted)
+     * Result of this function can be directly passed to ImFontAtlas
+     */
+    public short[] buildRanges() {
+        final List<Short> out = new ArrayList<>();
+        for (int n = 0; n <= UNICODE_CODEPOINT_MAX; n++) {
+            if (getBit(n)) {
+                out.add((short) n);
+                while (n < UNICODE_CODEPOINT_MAX && getBit(n + 1)) {
+                    n++;
+                }
+                out.add((short) n);
+            }
+        }
+
+        final short[] result = new short[out.size() + 1];
+        for (int i = 0; i < out.size(); i++) {
+            result[i] = out.get(i);
+        }
+        result[result.length - 1] = 0;
+        return result;
+    }
+
+    public void clear() {
+        Arrays.fill(usedChars, 0L);
+    }
+
+    public void setBit(final int n) {
+        final int off = n >> 5;
+        final long mask = 1L << (n & 31L);
+        usedChars[off] |= mask;
+    }
+
+    public boolean getBit(final int n) {
+        final int off = n >> 5;
+        final long mask = 1L << (n & 31L);
+        return (usedChars[off] & mask) > 0;
+    }
+
+
+}