Start progress on more advanced text layout

src/SDL.cake

@@ -517,7 +517,14 @@ Note that you can also build SDL manually. This can be useful if you are porting
   (Log "SDL: Successfully built\n")
   (return true))
 
-(add-dependency-git-submodule clone-sdl2 "https://github.com/libsdl-org/SDL" "Dependencies/SDL")
+(add-dependency-git-submodule
+ clone-sdl2
+ "https://github.com/libsdl-org/SDL"
+ "Dependencies/SDL"
+ ;; They changed their build system.
+ ;; TODO: Update to SDL3?
+ "2e9f5b5989c5140f47ce3ada603c1ae32d555f01")
+
 (add-compile-time-hook-module pre-build build-sdl)
 
 (export-and-evaluate

src/SDLFontAtlas.cake

@@ -3,8 +3,9 @@
 
 ;; SDLFontAtlas.cake: Render font atlases generated by FreeType.cake. This is kept separate from
 ;; both libraries in order to not force a dependency on either.
-(import "SDL.cake" "FreeType.cake" "Dictionary.cake"
-        "CHelpers.cake")
+(import "SDL.cake" "Dictionary.cake"
+        "CHelpers.cake"
+        &with-decls "FreeType.cake")
 
 (c-import &with-decls "<stdbool.h>")
 
@@ -18,11 +19,12 @@
 ;; The min and max arguments can be null. Otherwise, they are expected to be initialized to
 ;; reasonable values, e.g. positive infinity and negative infinity, respectively. This way, you can
 ;; render several strings separately and keep the same running bounds.
+;; When length-limit is 0, render until null terminator
 (defun render-string-internal (renderer (addr SDL_Renderer) font (addr font-atlas) font-texture (addr SDL_Texture)
                                write-x (addr int) write-y (addr int)
                                min-x-out (addr int) min-y-out (addr int)
                                max-x-out (addr int) max-y-out (addr int)
-                               str (addr (const char)))
+                               str (addr (const char)) length-limit (unsigned int))
 ;; TODO: Support UTF-8
   (var tab-width int 100)
   (scope ;; Get tab width based on space advance
@@ -39,6 +41,9 @@
   (var start-x int (deref write-x))
 
   (each-char-in-string-const str current-char
+    (when (and length-limit
+               (>= (- current-char str) length-limit))
+      (break))
     (cond
       ((= (deref current-char) '\r')
        (continue))
@@ -107,7 +112,49 @@
   (var write-y int y)
   (render-string-internal renderer font font-texture (addr write-x) (addr write-y)
                           null null null null
-                          str))
+                          str 0))
+
+(defun render-string-length (renderer (addr SDL_Renderer) font (addr font-atlas) font-texture (addr SDL_Texture)
+                             x int y int
+                             str (addr (const char)) length-limit (unsigned int))
+  (var write-x int x)
+  (var write-y int y)
+  (render-string-internal renderer font font-texture (addr write-x) (addr write-y)
+                          null null null null
+                          str length-limit))
+
+(defstruct font-render-settings
+  renderer (addr SDL_Renderer)
+  font (addr font-atlas) font-texture (addr SDL_Texture)
+  start-x int
+  ;; Relative to start-x
+  wrap-width-pixels int
+  r (unsigned char)
+  g (unsigned char)
+  b (unsigned char))
+
+(defstruct font-layout-state
+  x int
+  y int)
+
+;; If str-length-limit is 0, render string until null terminator
+(defun layout-render-string (render-settings (addr font-render-settings)
+                             state (addr font-layout-state)
+                             str (addr (const char)) str-length-limit (unsigned int))
+  (SDL_SetTextureColorMod
+   (path render-settings > font-texture)
+   (path render-settings > r) (path render-settings > g) (path render-settings > b))
+  (render-string-internal (path render-settings > renderer)
+                          (path render-settings > font)
+                          (path render-settings > font-texture)
+                          (addr (path state > x)) (addr (path state > y))
+                          null null null null
+                          str str-length-limit)
+  (ignore (when (>= (path state > x)
+            (+ (path render-settings > start-x)
+               (path render-settings > wrap-width-pixels)))
+    (set (path state > x) (path render-settings > start-x))
+    (set (path state > y) (+ (path state > y) (path render-settings > font > font-height))))))
 
 ;; Returns the minimum and maximum bounds of the rendered string relative to a (0, 0) baseline
 ;; Note that due to kerning, the width of 'l' + 'w' != 'lw', for example.
@@ -124,7 +171,7 @@
    (addr write-x) (addr write-y)
    min-x-out min-y-out
    max-x-out max-y-out
-   str))
+   str 0))
 
 (defun make-font-atlas-and-texture (renderer (addr SDL_Renderer)
                                     font-atlas-out (addr font-atlas) font-texture-out (addr (addr SDL_Texture))
@@ -158,6 +205,27 @@
      (return false)))
   (return true))
 
+(forward-declare (struct SDL_Texture))
+(defstruct font-atlas-texture
+  atlas font-atlas
+  texture (addr SDL_Texture))
+
+(defun font-atlas-texture-from-bundle-file (renderer (addr SDL_Renderer)
+                                            font-atlas-texture-out (addr font-atlas-texture)
+                                            font-data-start (addr (const (unsigned char)))
+                                            font-data-end (addr (const (unsigned char)))
+                                            device-dpi (unsigned int)
+                                            font-size-points (unsigned char)
+                                            &return bool)
+  (make-font-atlas-and-texture renderer
+                               (addr (path font-atlas-texture-out > atlas))
+                               (addr (path font-atlas-texture-out > texture))
+                               font-data-start
+                               (- font-data-end
+                                  font-data-start)
+                               device-dpi
+                               font-size-points))
+
 (comptime-cond
  ('auto-test
   (import "DataBundle.cake")