1 files changed, 43 insertions, 18 deletions

diff --git a/src/render.c b/src/render.c
index 51112a9..2fcade6 100644
--- a/src/render.c
+++ b/src/render.c
@@ -19,9 +19,9 @@ static const uiPixel uiPink  = {128, 0, 128, 255};
 /// We store a subsurface separate from the surface so that we can always check
 /// whether a given coordinate is within the bounds of the physical surface.
 typedef struct RenderState {
-  uiSurface surface;    /// Surface of pixels on which the UI is rendered.
-  uiRect    subsurface; /// Subregion where the current UI widget is rendered.
-  uiPoint   pen;        /// Current pen position relative to subsurface.
+  uiSurface surface;    ///< Surface of pixels on which the UI is rendered.
+  uiRect    subsurface; ///< Subregion where the current UI widget is rendered.
+  uiPoint   pen;        ///< Current pen position relative to subsurface.
 } RenderState;
 
 static void RenderWidget(RenderState* state, const uiWidget* widget);
@@ -165,6 +165,13 @@ static void RenderFrame(const uiFrame* frame, RenderState* state) {
   FillRect(&frame->widget.rect, uiBlack, state);
 }
 
+/// Render a button.
+static void RenderButton(const uiButton* button, RenderState* state) {
+  assert(button);
+  assert(state);
+  RenderText(string_data(button->text), string_length(button->text), state);
+}
+
 /// Render a label.
 static void RenderLabel(const uiLabel* label, RenderState* state) {
   assert(label);
@@ -253,14 +260,43 @@ static void RenderTable(const uiTable* table, RenderState* state) {
   }
 }
 
+void uiRender(const uiFrame* frame, uiSurface* surface) {
+  assert(frame);
+  assert(surface);
+
+  RenderWidget(
+      &(RenderState){
+          .surface    = *surface,
+          .subsurface = (uiRect){.x      = 0,
+                                 .y      = 0,
+                                 .width  = surface->width,
+                                 .height = surface->height},
+          .pen        = {.x = 0, .y = 0},
+  },
+      (const uiWidget*)frame);
+}
+
 /// Render a widget.
 static void RenderWidget(RenderState* state, const uiWidget* widget) {
   assert(state);
   assert(widget);
 
+  // A widget's position is relative to its parent's position.
+  // The pen currently points at the parent. Move it to this widget's position
+  // before rendering it, then render the widget's children using this new
+  // position.
+  // The pen's original position must be restored before returning, so save a
+  // copy here.
+  const uiPoint pen = state->pen;
+  state->pen =
+      (uiPoint){state->pen.x + widget->rect.x, state->pen.y + widget->rect.y};
+
   // Render this widget.
   switch (widget->type) {
+  case uiTypeLayout:
+    break;
   case uiTypeButton:
+    RenderButton((const uiButton*)widget, state);
     break;
   case uiTypeFrame:
     RenderFrame((const uiFrame*)widget, state);
@@ -268,6 +304,8 @@ static void RenderWidget(RenderState* state, const uiWidget* widget) {
   case uiTypeLabel:
     RenderLabel((const uiLabel*)widget, state);
     break;
+  case uiTypeEdit:
+    break;
   case uiTypeTable:
     RenderTable((const uiTable*)widget, state);
     break;
@@ -278,20 +316,7 @@ static void RenderWidget(RenderState* state, const uiWidget* widget) {
 
   // Render children.
   list_foreach(widget->children, child, { RenderWidget(state, child); });
-}
 
-void uiRender(const uiFrame* frame, uiSurface* surface) {
-  assert(frame);
-  assert(surface);
-
-  RenderWidget(
-      &(RenderState){
-          .surface    = *surface,
-          .subsurface = (uiRect){.x      = 0,
-                                 .y      = 0,
-                                 .width  = surface->width,
-                                 .height = surface->height},
-          .pen        = {.x = 0, .y = 0},
-  },
-      (const uiWidget*)frame);
+  // Restore the pen.
+  state->pen = pen;
 }