Check for SVG start tag and add tests

internal/c/parts/video/image/image.cpp

@@ -202,20 +202,16 @@ static uint32_t *image_svg_load_from_file(const char *fileName, int32_t *xOut, i
         fclose(fp);
         return nullptr;
     }
+    svgString[size] = '\0'; // must be null terminated
 
     fclose(fp);
 
-    // Bail if we have binary data
-    for (size_t i = 0; i < size; i++) {
-        uint8_t c = svgString[i];
-        if (c < 32 && c != '\0' && c != '\t' && c != '\r' && c != '\n') {
-            free(svgString);
-            return nullptr;
-        }
+    // Check if it has a valid SVG start tag
+    if (!strstr(svgString, "<svg")) {
+        free(svgString);
+        return nullptr;
     }
 
-    svgString[size] = '\0'; // must be null terminated
-
     auto image = nsvgParse(svgString, "px", 96.0f); // important note: changes the string
     if (!image) {
         free(svgString);
@@ -242,17 +238,15 @@ static uint32_t *image_svg_load_from_memory(const uint8_t *buffer, size_t size,
     if (!svgString)
         return nullptr;
 
-    // Bail if we have binary data. We'll also copy the data while doing the check to avoid another pass
-    for (size_t i = 0; i < size; i++) {
-        uint8_t c = svgString[i] = buffer[i];
-        if (c < 32 && c != '\0' && c != '\t' && c != '\r' && c != '\n') {
-            free(svgString);
-            return nullptr;
-        }
-    }
-
+    memcpy(svgString, buffer, size);
     svgString[size] = '\0'; // must be null terminated
 
+    // Check if it has a valid SVG start tag
+    if (!strstr(svgString, "<svg")) {
+        free(svgString);
+        return nullptr;
+    }
+
     auto image = nsvgParse(svgString, "px", 96.0f); // important note: changes the string
     if (!image) {
         free(svgString);

internal/c/parts/video/image/nanosvg/nanosvgrast.h

@@ -331,6 +331,7 @@ static float nsvg__normalize(float *x, float* y)
 }
 
 static float nsvg__absf(float x) { return x < 0 ? -x : x; }
+static float nsvg__roundf(float x) { return (x >= 0) ? floorf(x + 0.5) : ceilf(x - 0.5); }
 
 static void nsvg__flattenCubicBez(NSVGrasterizer* r,
 								  float x1, float y1, float x2, float y2,
@@ -872,10 +873,10 @@ static NSVGactiveEdge* nsvg__addActive(NSVGrasterizer* r, NSVGedge* e, float sta
 //	STBTT_assert(e->y0 <= start_point);
 	// round dx down to avoid going too far
 	if (dxdy < 0)
-		z->dx = (int)(-floorf(NSVG__FIX * -dxdy));
+		z->dx = (int)(-nsvg__roundf(NSVG__FIX * -dxdy));
 	else
-		z->dx = (int)floorf(NSVG__FIX * dxdy);
-	z->x = (int)floorf(NSVG__FIX * (e->x0 + dxdy * (startPoint - e->y0)));
+		z->dx = (int)nsvg__roundf(NSVG__FIX * dxdy);
+	z->x = (int)nsvg__roundf(NSVG__FIX * (e->x0 + dxdy * (startPoint - e->y0)));
 //	z->x -= off_x * FIX;
 	z->ey = e->y1;
 	z->next = 0;
@@ -1282,7 +1283,7 @@ static void nsvg__initPaint(NSVGcachedPaint* cache, NSVGpaint* paint, float opac
 	if (grad->nstops == 0) {
 		for (i = 0; i < 256; i++)
 			cache->colors[i] = 0;
-	} if (grad->nstops == 1) {
+	} else if (grad->nstops == 1) {
 		for (i = 0; i < 256; i++)
 			cache->colors[i] = nsvg__applyOpacity(grad->stops[i].color, opacity);
 	} else {

tests/compile_tests/image/bogus1.svg

@@ -0,0 +1 @@
+Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

tests/compile_tests/image/svg_test.bas

@@ -0,0 +1,26 @@
+$CONSOLE:ONLY
+OPTION _EXPLICIT
+
+DIM fileName AS STRING
+
+READ fileName
+WHILE LEN(fileName) > 0
+    DIM img AS LONG: img = _LOADIMAGE(fileName)
+
+    IF img < -1 THEN
+        PRINT fileName; ": ("; _WIDTH(img); "x"; _HEIGHT(img); ") pixels"
+        _FREEIMAGE img
+    ELSE
+        PRINT fileName; " is not a valid image file!"
+    END IF
+
+    READ fileName
+WEND
+
+SYSTEM
+
+DATA good1.svg
+DATA good2.svg
+DATA bogus1.svg
+DATA bogus2.svg
+DATA

tests/compile_tests/image/svg_test.output

@@ -0,0 +1,4 @@
+good1.svg: ( 493 x 800 ) pixels
+good2.svg: ( 493 x 800 ) pixels
+bogus1.svg is not a valid image file!
+bogus2.svg is not a valid image file!