feat: vector zoom for SVG in image viewer app

2026-05-18 20:15:22 +02:00
parent 72b9bd681b
commit 43c3c7e59b
4 changed files with 189 additions and 36 deletions
@@ -0,0 +1,72 @@
+/*
+ * svg_doc.cpp
+ * SvgDoc: source-backed rasterizable SVG document.
+ * Copyright (c) 2026 Daniel Hammer
+ */
+
+#include "svg_doc.hpp"
+
+#include <montauk/syscall.h>
+#include <montauk/heap.h>
+#include <gui/gui.hpp>
+#include <gui/svg.hpp>
+
+namespace imageviewer {
+
+bool svgdoc_init(SvgDoc* doc, uint8_t* source, int source_len) {
+    if (!doc) return false;
+    *doc = {};
+    if (!source || source_len <= 0) return false;
+
+    doc->source = source;
+    doc->source_len = source_len;
+    gui::svg_get_natural_size((const char*)source, source_len,
+                              &doc->natural_w, &doc->natural_h);
+    if (doc->natural_w < 1) doc->natural_w = 1;
+    if (doc->natural_h < 1) doc->natural_h = 1;
+    return true;
+}
+
+bool svgdoc_render(SvgDoc* doc, float target_scale, int max_edge) {
+    if (!doc || !doc->source) return false;
+    if (target_scale <= 0.0f) target_scale = 1.0f;
+    if (max_edge < 1) max_edge = 1;
+
+    // Clamp so the longest edge of the rasterized output stays within max_edge.
+    int natural_long = doc->natural_w > doc->natural_h ? doc->natural_w : doc->natural_h;
+    float max_scale = (float)max_edge / (float)natural_long;
+    if (target_scale > max_scale) target_scale = max_scale;
+    if (target_scale < 0.01f) target_scale = 0.01f;
+
+    // Skip if cache is already close enough (avoids re-render on float jitter).
+    if (doc->pixels && doc->render_scale > 0.0f) {
+        float ratio = target_scale / doc->render_scale;
+        if (ratio > 0.995f && ratio < 1.005f) return true;
+    }
+
+    int new_w = (int)((float)doc->natural_w * target_scale);
+    int new_h = (int)((float)doc->natural_h * target_scale);
+    if (new_w < 1) new_w = 1;
+    if (new_h < 1) new_h = 1;
+
+    gui::SvgIcon icon = gui::svg_render(
+        (const char*)doc->source, doc->source_len,
+        new_w, new_h, gui::Color::from_rgb(0, 0, 0));
+    if (!icon.pixels) return false;
+
+    if (doc->pixels) montauk::mfree(doc->pixels);
+    doc->pixels = icon.pixels;
+    doc->render_w = icon.width;
+    doc->render_h = icon.height;
+    doc->render_scale = target_scale;
+    return true;
+}
+
+void svgdoc_free(SvgDoc* doc) {
+    if (!doc) return;
+    if (doc->pixels) montauk::mfree(doc->pixels);
+    if (doc->source) montauk::mfree(doc->source);
+    *doc = {};
+}
+
+} // namespace imageviewer