Experimenting with text art

Convert glyph bitmaps to Unicode block characters

2 files changed, 113 insertions, 2 deletions

diff --git a/src/ui/text.c b/src/ui/text.c
index 0bf9b294..60e26692 100644
--- a/src/ui/text.c
+++ b/src/ui/text.c
@@ -11,6 +11,7 @@
 #include <the_Foundation/file.h>
 #include <the_Foundation/hash.h>
 #include <the_Foundation/math.h>
+#include <the_Foundation/stringlist.h>
 #include <the_Foundation/regexp.h>
 #include <the_Foundation/path.h>
 #include <the_Foundation/vec2.h>
@@ -287,8 +288,8 @@ static void cache_Font_(iFont *d, iGlyph *glyph, int hoff) {
     /* Rasterize the glyph using stbtt. */ {
         surface = rasterizeGlyph_Font_(d, ch, hoff * 0.5f);
         if (hoff == 0) {
-            int adv, lsb;
-            stbtt_GetCodepointHMetrics(&d->font, ch, &adv, &lsb);
+            int adv;
+            stbtt_GetCodepointHMetrics(&d->font, ch, &adv, NULL);
             glyph->advance = d->scale * adv;
         }
         stbtt_GetCodepointBitmapBoxSubpixel(&d->font,
@@ -658,6 +659,111 @@ SDL_Texture *glyphCache_Text(void) {
     return text_.cache;
 }
 
+static void freeBitmap_(void *ptr) {
+    stbtt_FreeBitmap(ptr, NULL);
+}
+
+iString *renderBlockChars_Text(const iBlock *fontData, int height, enum iTextBlockMode mode,
+                               const iString *text) {
+    iBeginCollect();
+    stbtt_fontinfo font;
+    iZap(font);
+    stbtt_InitFont(&font, constData_Block(fontData), 0);
+    int ascent;
+    stbtt_GetFontVMetrics(&font, &ascent, NULL, NULL);
+    iDeclareType(CharBuf);
+    struct Impl_CharBuf {
+        uint8_t *pixels;
+        iInt2 size;
+        int dy;
+        int advance;
+    };
+    iArray *    chars     = collectNew_Array(sizeof(iCharBuf));
+    int         pxRatio   = (mode == quadrants_TextBlockMode ? 2 : 1);
+    int         pxHeight  = height * pxRatio;
+    const float scale     = stbtt_ScaleForPixelHeight(&font, pxHeight);
+    const float xScale    = scale * 2; /* character aspect ratio */
+    const int   baseline  = ascent * scale;
+    int         width     = 0;
+    size_t      strRemain = length_String(text);
+    iConstForEach(String, i, text) {
+        if (!strRemain) break;
+        if (i.value == variationSelectorEmoji_Char) {
+            strRemain--;
+            continue;
+        }
+        iCharBuf buf;
+        buf.pixels = stbtt_GetCodepointBitmap(
+            &font, xScale, scale, i.value, &buf.size.x, &buf.size.y, 0, &buf.dy);
+        stbtt_GetCodepointHMetrics(&font, i.value, &buf.advance, NULL);
+        buf.advance *= xScale;
+        if (!isSpace_Char(i.value)) {
+            if (mode == quadrants_TextBlockMode) {
+                buf.advance = (buf.size.x - 1) / 2 * 2 + 2;
+            }
+            else {
+                buf.advance = buf.size.x + 1;
+            }
+        }
+        pushBack_Array(chars, &buf);
+        collect_Garbage(buf.pixels, freeBitmap_);
+        width += buf.advance;
+        strRemain--;
+    }
+    const size_t len = (mode == quadrants_TextBlockMode ? height * ((width + 1) / 2 + 1)
+                                                        : (height * (width + 1)));
+    iChar *outBuf = iCollectMem(malloc(sizeof(iChar) * len));
+    for (size_t i = 0; i < len; ++i) {
+        outBuf[i] = 0x20;
+    }
+    iChar *outPos = outBuf;
+    for (int y = 0; y < pxHeight; y += pxRatio) {
+        const iCharBuf *ch = constData_Array(chars);
+        int lx = 0;
+        for (int x = 0; x < width; x += pxRatio, lx += pxRatio) {
+            if (lx >= ch->advance) {
+                ch++;
+                lx = 0;
+            }
+            const int ly = y - baseline - ch->dy;
+            if (mode == quadrants_TextBlockMode) {
+                #define checkPixel_(offx, offy) \
+                    (lx + offx < ch->size.x && ly + offy < ch->size.y && ly + offy >= 0 ? \
+                        ch->pixels[(lx + offx) + (ly + offy) * ch->size.x] > 155 \
+                        : iFalse)
+                const int mask = (checkPixel_(0, 0) ? 1 : 0) |
+                                 (checkPixel_(1, 0) ? 2 : 0) |
+                                 (checkPixel_(0, 1) ? 4 : 0) |
+                                 (checkPixel_(1, 1) ? 8 : 0);
+                #undef checkPixel_
+                static const iChar blocks[16] = { 0x0020, 0x2598, 0x259D, 0x2580, 0x2596, 0x258C,
+                                                  0x259E, 0x259B, 0x2597, 0x259A, 0x2590, 0x259C,
+                                                  0x2584, 0x2599, 0x259F, 0x2588 };
+                *outPos++ = blocks[mask];
+            }
+            else {
+                static const iChar shades[5] = { 0x0020, 0x2591, 0x2592, 0x2593, 0x2588 };
+                *outPos++ = shades[lx < ch->size.x && ly < ch->size.y && ly >= 0 ?
+                                   ch->pixels[lx + ly * ch->size.x] * 5 / 256 : 0];
+            }
+        }
+        *outPos++ = '\n';
+    }
+    /* We could compose the lines separately, but we'd still need to convert them to Strings
+       individually to trim them. */
+    iStringList *lines = split_String(collect_String(newUnicodeN_String(outBuf, len)), "\n");
+    while (!isEmpty_StringList(lines) &&
+           isEmpty_String(collect_String(trimmed_String(at_StringList(lines, 0))))) {
+        popFront_StringList(lines);
+    }
+    while (!isEmpty_StringList(lines) && isEmpty_String(collect_String(trimmed_String(
+                                             at_StringList(lines, size_StringList(lines) - 1))))) {
+        popBack_StringList(lines);
+    }
+    iEndCollect();
+    return joinCStr_StringList(iClob(lines), "\n");
+}
+
 /*-----------------------------------------------------------------------------------------------*/
 
 iDefineTypeConstructionArgs(TextBuf, (int font, const char *text), font, text)
diff --git a/src/ui/text.h b/src/ui/text.h
index 2d49a1a6..239fae51 100644
--- a/src/ui/text.h
+++ b/src/ui/text.h
@@ -90,6 +90,11 @@ void    drawRange_Text      (int fontId, iInt2 pos, int color, iRangecc text);
 
 SDL_Texture *   glyphCache_Text     (void);
 
+enum iTextBlockMode { quadrants_TextBlockMode, shading_TextBlockMode };
+
+iString *   renderBlockChars_Text   (const iBlock *fontData, int height, enum iTextBlockMode,
+                                     const iString *text);
+
 /*-----------------------------------------------------------------------------------------------*/
 
 iDeclareType(TextBuf)