Add and optimize text rendering functions

New functions operate on two char*'s in the event strings are not null terminated
* MeasureTextViewEx
* MeasureTextView
* DrawTextViewEx
* DrawTextViewPro

Rewrote some conditional operations as math in DrawTexturePro to try to get compiler
to generate branchless code even in debug mode.

src/raylib.h

@@ -1362,16 +1362,22 @@ RLAPI void UnloadFont(Font font);
 RLAPI bool ExportFontAsCode(Font font, const char *fileName);                               // Export font as code file, returns true on success
 
 // Text drawing functions
+RLAPI void DrawTextViewEx(Font font, const char* text, const char* textEnd, Vector2 position, float fontSize, float spacing, Color tint);
 RLAPI void DrawFPS(int posX, int posY);                                                     // Draw current FPS
 RLAPI void DrawText(const char *text, int posX, int posY, int fontSize, Color color);       // Draw text (using default font)
 RLAPI void DrawTextEx(Font font, const char *text, Vector2 position, float fontSize, float spacing, Color tint); // Draw text using font and additional parameters
 RLAPI void DrawTextPro(Font font, const char *text, Vector2 position, Vector2 origin, float rotation, float fontSize, float spacing, Color tint); // Draw text using Font and pro parameters (rotation)
+RLAPI void DrawTextViewPro(Font font, const char* text, const char* textEnd, Vector2 position, Vector2 origin, float rotation, float fontSize, float spacing, Color tint);
+
 RLAPI void DrawTextCodepoint(Font font, int codepoint, Vector2 position, float fontSize, Color tint); // Draw one character (codepoint)
 RLAPI void DrawTextCodepoints(Font font, const int *codepoints, int count, Vector2 position, float fontSize, float spacing, Color tint); // Draw multiple character (codepoint)
 
 // Text font info functions
 RLAPI int MeasureText(const char *text, int fontSize);                                      // Measure string width for default font
 RLAPI Vector2 MeasureTextEx(Font font, const char *text, float fontSize, float spacing);    // Measure string size for Font
+RLAPI int MeasureTextView(const char* text, const char* textEnd, int fontSize);                                      // Measure string width for default font
+RLAPI Vector2 MeasureTextViewEx(Font font, const char* text, const char* textEnd, float fontSize, float spacing);    // Measure string size for Font
+
 RLAPI int GetGlyphIndex(Font font, int codepoint);                                          // Get glyph index position in font for a codepoint (unicode character), fallback to '?' if not found
 RLAPI GlyphInfo GetGlyphInfo(Font font, int codepoint);                                     // Get glyph font info data for a codepoint (unicode character), fallback to '?' if not found
 RLAPI Rectangle GetGlyphAtlasRec(Font font, int codepoint);                                 // Get glyph rectangle in font atlas for a codepoint (unicode character), fallback to '?' if not found

src/rtext.c

@@ -1015,8 +1015,7 @@ void DrawFPS(int posX, int posY)
     Color color = LIME;                         // Good FPS
     int fps = GetFPS();
 
-    if ((fps < 30) && (fps >= 15)) color = ORANGE;  // Warning FPS
+    color = (fps >= 30) ? color : (fps >= 15) ? ORANGE : RED;
-    else if (fps < 15) color = RED;             // Low FPS
 
     DrawText(TextFormat("%2i FPS", GetFPS()), posX, posY, 20, color);
 }
@@ -1039,20 +1038,18 @@ void DrawText(const char *text, int posX, int posY, int fontSize, Color color)
     }
 }
 
-// Draw text using Font
+void DrawTextViewEx(Font font, const char* text, const char* textEnd, Vector2 position, float fontSize, float spacing, Color tint)
-// NOTE: chars spacing is NOT proportional to fontSize
-void DrawTextEx(Font font, const char *text, Vector2 position, float fontSize, float spacing, Color tint)
 {
     if (font.texture.id == 0) font = GetFontDefault();  // Security check in case of not valid font
 
-    int size = TextLength(text);    // Total size in bytes of the text, scanned by codepoints in loop
+    int bytes = textEnd - text; // Total size in bytes of the text, scanned by codepoints in loop
 
     int textOffsetY = 0;            // Offset between lines (on linebreak '\n')
     float textOffsetX = 0.0f;       // Offset X to next character to draw
 
     float scaleFactor = fontSize / font.baseSize;         // Character quad scaling factor
 
-    for (int i = 0; i < size;)
+    for (int i = 0; i < bytes;)
     {
         // Get next codepoint from byte string and glyph index in font
         int codepointByteCount = 0;
@@ -1085,6 +1082,28 @@ void DrawTextEx(Font font, const char *text, Vector2 position, float fontSize, f
     }
 }
 
+// Draw text using Font and pro parameters (rotation)
+void DrawTextViewPro(Font font, const char* text, const char* textEnd, Vector2 position, Vector2 origin, float rotation, float fontSize, float spacing, Color tint)
+{
+    rlPushMatrix();
+
+    rlTranslatef(position.x, position.y, 0.0f);
+    rlRotatef(rotation, 0.0f, 0.0f, 1.0f);
+    rlTranslatef(-origin.x, -origin.y, 0.0f);
+
+    DrawTextViewEx(font, text, textEnd, (Vector2) { 0.0f, 0.0f }, fontSize, spacing, tint);
+
+    rlPopMatrix();
+}
+
+// Draw text using Font
+// NOTE: chars spacing is NOT proportional to fontSize
+void DrawTextEx(Font font, const char *text, Vector2 position, float fontSize, float spacing, Color tint)
+{
+    int size = TextLength(text);    // Total size in bytes of the text, scanned by codepoints in loop
+    DrawTextViewEx(font, text, text + size, position, fontSize, spacing, tint);
+}
+
 // Draw text using Font and pro parameters (rotation)
 void DrawTextPro(Font font, const char *text, Vector2 position, Vector2 origin, float rotation, float fontSize, float spacing, Color tint)
 {
@@ -1173,14 +1192,32 @@ int MeasureText(const char *text, int fontSize)
     return (int)textSize.x;
 }
 
+// Measure string width for default font
+int MeasureTextView(const char* text, const char* textEnd, int fontSize) {
+    Vector2 textSize = { 0.0f, 0.0f };
+
+    // Check if default font has been loaded
+    if (GetFontDefault().texture.id != 0)
+    {
+        int defaultFontSize = 10;   // Default Font chars height in pixel
+        if (fontSize < defaultFontSize) fontSize = defaultFontSize;
+        int spacing = fontSize / defaultFontSize;
+
+        textSize = MeasureTextViewEx(GetFontDefault(), text, textEnd, (float)fontSize, (float)spacing);
+    }
+
+    return (int)textSize.x;
+}
+
 // Measure string size for Font
-Vector2 MeasureTextEx(Font font, const char *text, float fontSize, float spacing)
+Vector2 MeasureTextViewEx(Font font, const char* text, const char* textEnd, float fontSize, float spacing)
 {
     Vector2 textSize = { 0 };
 
     if ((font.texture.id == 0) || (text == NULL)) return textSize;
 
-    int size = TextLength(text);    // Get size in bytes of text
+    //int size = TextLength(text);    
+    int size = textEnd - text; // Get size in bytes of text
     int tempByteCounter = 0;        // Used to count longer text line num chars
     int byteCounter = 0;
 
@@ -1229,6 +1266,11 @@ Vector2 MeasureTextEx(Font font, const char *text, float fontSize, float spacing
 
     return textSize;
 }
+Vector2 MeasureTextEx(Font font, const char *text, float fontSize, float spacing)
+{
+    int size = TextLength(text);    // Get size in bytes of text
+    return MeasureTextViewEx(font, text, text + size, fontSize, spacing);
+}
 
 // Get index position for a unicode character on font
 // NOTE: If codepoint is not found in the font it fallbacks to '?'

src/rtextures.c

@@ -3546,10 +3546,10 @@ void DrawTexturePro(Texture2D texture, Rectangle source, Rectangle dest, Vector2
         float width = (float)texture.width;
         float height = (float)texture.height;
 
-        bool flipX = false;
+        bool flipX = source.width < 0;
 
-        if (source.width < 0) { flipX = true; source.width *= -1; }
+        source.width = flipX ? source.width * -1 : source.width;
-        if (source.height < 0) source.y -= source.height;
+        source.y -= (source.height < 0) ? source.height : 0.0f;
 
         Vector2 topLeft = { 0 };
         Vector2 topRight = { 0 };
@@ -3594,24 +3594,29 @@ void DrawTexturePro(Texture2D texture, Rectangle source, Rectangle dest, Vector2
             rlColor4ub(tint.r, tint.g, tint.b, tint.a);
             rlNormal3f(0.0f, 0.0f, 1.0f);                          // Normal vector pointing towards viewer
 
+            float right_edge_x = (source.x + source.width) / width;
+            float left_edge_x = source.x / width;
+            float bottom_edge_y = (source.y + source.height) / height;
+            float top_edge_y = source.y / height;
+
+            // Should communicate the non-branchy version of this expression to the compiler
+            float l_edge = (flipX * right_edge_x) + (!flipX * left_edge_x);//flipX ? right_edge_x : left_edge_x;
+            float r_edge = (flipX * left_edge_x) + (!flipX * right_edge_x);//flipX ? left_edge_x : right_edge_x;
+
             // Top-left corner for texture and quad
-            if (flipX) rlTexCoord2f((source.x + source.width)/width, source.y/height);
+            rlTexCoord2f(l_edge, top_edge_y);
-            else rlTexCoord2f(source.x/width, source.y/height);
             rlVertex2f(topLeft.x, topLeft.y);
 
             // Bottom-left corner for texture and quad
-            if (flipX) rlTexCoord2f((source.x + source.width)/width, (source.y + source.height)/height);
+            rlTexCoord2f(l_edge, bottom_edge_y);
-            else rlTexCoord2f(source.x/width, (source.y + source.height)/height);
             rlVertex2f(bottomLeft.x, bottomLeft.y);
 
             // Bottom-right corner for texture and quad
-            if (flipX) rlTexCoord2f(source.x/width, (source.y + source.height)/height);
+            rlTexCoord2f(r_edge, bottom_edge_y);
-            else rlTexCoord2f((source.x + source.width)/width, (source.y + source.height)/height);
             rlVertex2f(bottomRight.x, bottomRight.y);
 
             // Top-right corner for texture and quad
-            if (flipX) rlTexCoord2f(source.x/width, source.y/height);
+            rlTexCoord2f(r_edge, top_edge_y);
-            else rlTexCoord2f((source.x + source.width)/width, source.y/height);
             rlVertex2f(topRight.x, topRight.y);
 
         rlEnd();