1 files changed, 690 insertions, 0 deletions

diff --git a/src/ui.c b/src/ui.c
new file mode 100644
index 0000000..a5ab8d3
--- /dev/null
+++ b/src/ui.c
@@ -0,0 +1,690 @@
+#include <ui.h>
+
+#include <cassert.h>
+#include <cstring.h>
+#include <font.h>
+#include <list.h>
+
+#include <stdlib.h>
+
+static void* uiAlloc(size_t count, size_t size) {
+  void* mem = calloc(count, size);
+  ASSERT(mem);
+  return mem;
+}
+
+#define UI_NEW(TYPE) (TYPE*)uiAlloc(1, sizeof(TYPE))
+#define UI_DEL(ppWidget)       \
+  {                            \
+    assert(ppWidget);          \
+    void* widget_ = *ppWidget; \
+    if (widget_) {             \
+      free(widget_);           \
+      *ppWidget = 0;           \
+    }                          \
+  }
+
+DEF_LIST(Widget, uiWidget*)
+
+/// Base widget type.
+typedef struct uiWidget {
+  uiWidgetType type;
+  uiRect       rect;
+  Widget_list  children;
+} uiWidget;
+
+/// Button.
+typedef struct uiButton {
+  uiWidget widget;
+  string   text;
+} uiButton;
+
+/// Frame.
+typedef struct uiFrame {
+  uiWidget widget;
+} uiFrame;
+
+/// Label.
+typedef struct uiLabel {
+  uiWidget widget;
+  string   text;
+} uiLabel;
+
+/// Table cell.
+typedef struct uiCell {
+  uiWidget* child;
+} uiCell;
+
+/// Table.
+typedef struct uiTable {
+  uiWidget widget;
+  int      rows;
+  int      cols;
+  int*     widths; /// Width, in pixels, for each each column.
+  uiCell*  header; /// If non-null, row of 'cols' header cells.
+  uiCell*  cells;  /// Array of 'rows * cols' cells.
+} uiTable;
+
+typedef struct uiLibrary {
+  FontAtlas* font;
+} uiLibrary;
+
+// -----------------------------------------------------------------------------
+// Library.
+
+uiLibrary g_ui = {0};
+
+bool uiInit(void) {
+  // TODO: Embed the font into the library instead.
+  const char* font_path = "../ui/fontbaker/NK57.bin";
+  if (!(g_ui.font = LoadFontAtlas(font_path))) {
+    return false;
+  }
+
+  // TODO: Remove.
+  const FontHeader* header     = &g_ui.font->header;
+  const int         glyph_size = header->glyph_width * header->glyph_height;
+  const int         atlas_size = header->num_glyphs * glyph_size;
+  printf("Loaded font: %s\n", font_path);
+  printf(
+      "Glyph: %dx%d (%d bytes)\n", header->glyph_width, header->glyph_height,
+      glyph_size);
+  printf(
+      "Atlas: %dx%d (%d bytes)\n", header->num_glyphs * header->glyph_width,
+      header->glyph_height, atlas_size);
+
+  return true;
+}
+
+void uiShutdown(void) {}
+
+// -----------------------------------------------------------------------------
+// Widget.
+
+static uiButton* uiGetButtonPtr(uiWidgetPtr ptr) {
+  assert(ptr.type == uiTypeButton);
+  assert(ptr.button);
+  return ptr.button;
+}
+
+static uiFrame* uiGetFramePtr(uiWidgetPtr ptr) {
+  assert(ptr.type == uiTypeFrame);
+  assert(ptr.frame);
+  return ptr.frame;
+}
+
+static uiLabel* uiGetLabelPtr(uiWidgetPtr ptr) {
+  assert(ptr.type == uiTypeLabel);
+  assert(ptr.label);
+  return ptr.label;
+}
+
+static uiTable* uiGetTablePtr(uiWidgetPtr ptr) {
+  assert(ptr.type == uiTypeTable);
+  assert(ptr.table);
+  return ptr.table;
+}
+
+static void DestroyWidget(uiWidget** ppWidget) {
+  assert(ppWidget);
+
+  uiWidget* widget = *ppWidget;
+  if (widget) {
+    list_foreach_mut(widget->children, child, { DestroyWidget(&child); });
+  }
+  UI_DEL(ppWidget);
+}
+
+uiWidgetPtr uiMakeButtonPtr(uiButton* button) {
+  assert(button);
+  return (uiWidgetPtr){.type = uiTypeButton, .button = button};
+}
+
+uiWidgetPtr uiMakeFramePtr(uiFrame* frame) {
+  assert(frame);
+  return (uiWidgetPtr){.type = uiTypeFrame, .frame = frame};
+}
+
+uiWidgetPtr uiMakeLabelPtr(uiLabel* label) {
+  assert(label);
+  return (uiWidgetPtr){.type = uiTypeLabel, .label = label};
+}
+
+uiWidgetPtr uiMakeTablePtr(uiTable* table) {
+  assert(table);
+  return (uiWidgetPtr){.type = uiTypeTable, .table = table};
+}
+
+void uiWidgetSetParent(uiWidgetPtr child_, uiWidgetPtr parent_) {
+  uiWidget* child  = child_.widget;
+  uiWidget* parent = parent_.widget;
+
+  assert(child);
+  assert(parent);
+
+  list_add(parent->children, child);
+}
+
+// -----------------------------------------------------------------------------
+// Button.
+
+uiButton* uiMakeButton(const char* text) {
+  assert(text);
+
+  uiButton* button = UI_NEW(uiButton);
+
+  *button = (uiButton){
+      .widget =
+          (uiWidget){
+                     .type = uiTypeButton,
+                     .rect = {0},
+                     },
+      .text = string_new(text),
+  };
+  return button;
+}
+
+// -----------------------------------------------------------------------------
+// Label.
+
+uiLabel* uiMakeLabel(const char* text) {
+  assert(text);
+
+  uiLabel* label = UI_NEW(uiLabel);
+
+  *label = (uiLabel){
+      .widget =
+          (uiWidget){
+                     .type = uiTypeLabel,
+                     },
+      .text = string_new(text),
+  };
+  return label;
+}
+
+// -----------------------------------------------------------------------------
+// Frame.
+
+uiFrame* uiMakeFrame(void) {
+  uiFrame* frame     = UI_NEW(uiFrame);
+  frame->widget.type = uiTypeFrame;
+  return frame;
+}
+
+void uiDestroyFrame(uiFrame** ppFrame) { DestroyWidget((uiWidget**)ppFrame); }
+
+uiSize uiGetFrameSize(const uiFrame* frame) {
+  assert(frame);
+  return (uiSize){
+      .width  = frame->widget.rect.width,
+      .height = frame->widget.rect.height,
+  };
+}
+
+// -----------------------------------------------------------------------------
+// Table.
+
+static const uiCell* GetCell(const uiTable* table, int row, int col) {
+  assert(table);
+  return table->cells + (row * table->cols) + col;
+}
+
+static uiCell* GetCellMut(uiTable* table, int row, int col) {
+  assert(table);
+  return (uiCell*)GetCell(table, row, col);
+}
+
+static uiCell* GetLastRow(uiTable* table) {
+  assert(table);
+  assert(table->rows > 0);
+  return &table->cells[table->cols * (table->rows - 1)];
+}
+
+uiTable* uiMakeTable(int rows, int cols, const char** header) {
+  uiTable* table = UI_NEW(uiTable);
+
+  *table = (uiTable){
+      .widget = (uiWidget){.type = uiTypeTable},
+      .rows   = rows,
+      .cols   = cols,
+      .widths = (cols > 0) ? calloc(cols, sizeof(int)) : 0,
+      .header = header ? calloc(cols, sizeof(uiCell)) : 0,
+      .cells  = (rows * cols > 0) ? calloc(rows * cols, sizeof(uiCell)) : 0,
+  };
+
+  if (header) {
+    for (int col = 0; col < cols; ++col) {
+      table->header[col].child = (uiWidget*)uiMakeLabel(header[col]);
+    }
+  }
+
+  return table;
+}
+
+void uiTableAddRow(uiTable* table, const char** row) {
+  assert(table);
+
+  table->rows++;
+
+  uiCell* cells =
+      realloc(table->cells, table->rows * table->cols * sizeof(uiCell));
+  assert(cells);
+  table->cells = cells;
+
+  uiCell* cell = GetLastRow(table);
+  for (int col = 0; col < table->cols; ++col, ++cell) {
+    cell->child = (uiWidget*)uiMakeLabel(row[col]);
+  }
+}
+
+void uiTableSet(uiTable* table, int row, int col, uiWidgetPtr child) {
+  assert(table);
+  assert(child.widget);
+
+  GetCellMut(table, row, col)->child = child.widget;
+}
+
+const uiWidget* uiTableGet(const uiTable* table, int row, int col) {
+  assert(table);
+  return GetCell(table, row, col)->child;
+}
+
+uiWidget* uiTableGetMut(uiTable* table, int row, int col) {
+  assert(table);
+  return GetCellMut(table, row, col)->child;
+}
+
+// -----------------------------------------------------------------------------
+// Layout and resizing.
+
+static void ResizeTable(uiTable* table, int width, int height) {
+  assert(table);
+
+  if (table->cols == 0) {
+    return;
+  }
+
+  // Surface width: W.
+  // Columns: N
+  //
+  // First, find the minimum width of each column based on their contents.
+  //
+  // If the sum of column widths < N, then distribute the extra space first
+  // among the smallest columns and building up towards the larger.
+  //
+  // If the sum of column widths > N, subtract from the largest column first and
+  // move towards the smaller ones to distribute the space as evenly as
+  // possible.
+
+  // Find the minimum width for each column.
+  int* widths = table->widths;
+  // Header.
+  for (int col = 0; col < table->cols; ++col) {
+    const uiCell*  cell   = &table->header[col];
+    const uiLabel* label  = (uiLabel*)cell->child;
+    const int      length = (int)string_length(label->text);
+
+    widths[col] = length;
+  }
+  // Table contents.
+  for (int row = 0; row < table->rows; ++row) {
+    for (int col = 0; col < table->cols; ++col) {
+      const uiCell* cell = GetCell(table, row, col);
+      if (cell->child) {
+        const uiLabel* label  = (uiLabel*)cell->child;
+        const int      length = (int)string_length(label->text);
+
+        widths[col] = length > widths[col] ? length : widths[col];
+      }
+    }
+  }
+  // Multiply string lengths times glyph width to compute pixel size.
+  for (int col = 0; col < table->cols; ++col) {
+    widths[col] *= g_ui.font->header.glyph_width;
+  }
+
+  // Find the sum of widths.
+  int used_width = 0;
+  for (int col = 0; col < table->cols; ++col) {
+    used_width += widths[col];
+  }
+
+  // Pad if available width is larger than sum of widths.
+  if (used_width < width) {
+    // Divide evenly among columns.
+    // const int extra = width - used_width;
+    //    const int pad   = extra / table->cols;
+    //    const int mod   = extra % table->cols;
+    //    for (int col = 0; col < table->cols; ++col) {
+    //      table->widths[col] += pad + (col < mod ? 1 : 0);
+    //    }
+
+    int extra = width - used_width;
+    while (extra > 0) {
+      // Find smallest column.
+      int smallest = 0;
+      for (int col = 1; col < table->cols; ++col) {
+        if (widths[col] < widths[smallest]) {
+          smallest = col;
+        }
+      }
+      // Pad it and subtract from the budget.
+      widths[smallest] += 1;
+      extra--;
+    }
+  }
+  // Shrink if available width is smaller than the sum of widths.
+  else if (used_width > width) {
+    int deficit = used_width - width;
+    while (deficit > 0) {
+      // Find largest column.
+      int largest = 0;
+      for (int col = 1; col < table->cols; ++col) {
+        if (widths[col] > widths[largest]) {
+          largest = col;
+        }
+      }
+      // Shrink it and subtract from the deficit.
+      widths[largest] -= 1;
+      deficit--;
+    }
+  }
+}
+
+static void ResizeWidget(uiWidget* widget, int width, int height) {
+  assert(widget);
+
+  widget->rect.width  = width;
+  widget->rect.height = height;
+
+  switch (widget->type) {
+  case uiTypeButton:
+    break;
+  case uiTypeFrame:
+    list_foreach_mut(
+        widget->children, child, { ResizeWidget(child, width, height); });
+    break;
+  case uiTypeLabel:
+    break;
+  case uiTypeTable:
+    ResizeTable((uiTable*)widget, width, height);
+    break;
+  case uiTypeMax:
+    TRAP();
+    break;
+  }
+}
+
+void uiResizeFrame(uiFrame* frame, int width, int height) {
+  assert(frame);
+  ResizeWidget(&frame->widget, width, height);
+}
+
+// -----------------------------------------------------------------------------
+// Rendering.
+
+static const uiPixel uiBlack = {40, 40, 40, 255};
+static const uiPixel uiWhite = {255, 255, 255, 255};
+static const uiPixel uiPink  = {128, 0, 128, 255};
+
+/// Render state.
+///
+/// Render functions are allowed to manipulate the state internally (e.g., the
+/// subsurface), but must leave the state intact before returning, except, of
+/// course, for the rendered pixels.
+///
+/// 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.
+} RenderState;
+
+static void RenderWidget(RenderState* state, const uiWidget* widget);
+
+void PushSubsurface(
+    RenderState* state, int width, int height, uiRect* original_subsurface,
+    uiPoint* original_pen) {
+  assert(state);
+  assert(original_subsurface);
+  assert(original_pen);
+
+  *original_subsurface = state->subsurface;
+  *original_pen        = state->pen;
+
+  state->subsurface.x      = state->subsurface.x + state->pen.x;
+  state->subsurface.width  = width;
+  state->subsurface.height = height;
+  state->pen.x             = 0;
+}
+
+void PopSubsurface(
+    RenderState* state, const uiRect* original_subsurface,
+    const uiPoint* original_pen) {
+  assert(state);
+  assert(original_subsurface);
+  assert(original_pen);
+
+  state->subsurface = *original_subsurface;
+  state->pen        = *original_pen;
+}
+
+/// Checks whether pen + (w,h) is within the surface and subsurface.
+static bool PenInSurface(const RenderState* state, int w, int h) {
+  assert(state);
+
+  // Surface.
+  const bool in_surface =
+      ((state->subsurface.x + state->pen.x + w) < state->surface.width) &&
+      ((state->subsurface.y + state->pen.y + h) < state->surface.height);
+
+  // Subsurface.
+  const bool in_subsurface = ((state->pen.x + w) < state->subsurface.width) &&
+                             ((state->pen.y + h) < state->subsurface.height);
+
+  return in_surface && in_subsurface;
+}
+
+/// Get the pixel at (x,y).
+static uiPixel* SurfaceXy(uiSurface* surface, int x, int y) {
+  assert(surface);
+  assert(x >= 0);
+  assert(y >= 0);
+  assert(x < surface->width);
+  assert(y < surface->height);
+  return surface->pixels + (surface->width * y) + x;
+}
+
+/// Get the pixel at pen + (x,y).
+static uiPixel* PixelXy(RenderState* state, int x, int y) {
+  assert(state);
+  return SurfaceXy(
+      &state->surface, state->subsurface.x + state->pen.x + x,
+      state->subsurface.y + state->pen.y + y);
+}
+
+static void FillRect(const uiRect* rect, uiPixel colour, RenderState* state) {
+  assert(rect);
+  assert(state);
+  assert(rect->width <= state->subsurface.width);
+  assert(rect->height <= state->subsurface.height);
+
+  for (int y = rect->y; y < rect->y + rect->height; ++y) {
+    uiPixel* pixel = PixelXy(state, rect->x, y);
+    for (int x = rect->x; x < rect->x + rect->width; ++x) {
+      *pixel++ = colour;
+    }
+  }
+}
+
+/// Render a glyph.
+/// The glyph is clamped to the surface's bounds.
+static void RenderGlyph(
+    const FontAtlas* atlas, unsigned char c, RenderState* state) {
+  assert(atlas);
+  assert(state);
+  assert(atlas->header.glyph_width <= state->subsurface.width);
+  assert(atlas->header.glyph_height <= state->subsurface.height);
+
+  const int glyph_width  = atlas->header.glyph_width;
+  const int glyph_height = atlas->header.glyph_height;
+
+  const unsigned char* glyph = FontGetGlyph(atlas, c);
+
+  for (int y = 0; (y < atlas->header.glyph_height) &&
+                  PenInSurface(state, glyph_width - 1, glyph_height - 1);
+       ++y) {
+    for (int x = 0; (x < atlas->header.glyph_width) &&
+                    PenInSurface(state, glyph_width - 1, glyph_height - 1);
+         ++x, ++glyph) {
+      uiPixel* pixel = PixelXy(state, x, y);
+      if (*glyph > 0) {
+        pixel->r = *glyph;
+        pixel->g = *glyph;
+        pixel->b = *glyph;
+        pixel->a = 255;
+      }
+    }
+  }
+}
+
+static void RenderText(const char* text, size_t length, RenderState* state) {
+  assert(text);
+  assert(state);
+
+  const FontAtlas* atlas = g_ui.font;
+
+  const int glyph_width  = atlas->header.glyph_width;
+  const int glyph_height = atlas->header.glyph_height;
+
+  // Save the x-pen so that we can restore it after rendering the text.
+  const int x0 = state->pen.x;
+
+  // Truncate the text rendering if it exceeds the subsurface's width or height.
+  const char* c = text;
+  for (size_t i = 0;
+       (i < length) && PenInSurface(state, glyph_width - 1, glyph_height - 1);
+       ++i, ++c, state->pen.x += glyph_width) {
+    RenderGlyph(atlas, *c, state);
+  }
+
+  state->pen.x = x0;
+}
+
+static void RenderFrame(const uiFrame* frame, RenderState* state) {
+  assert(frame);
+
+  FillRect(&frame->widget.rect, uiBlack, state);
+}
+
+static void RenderLabel(const uiLabel* label, RenderState* state) {
+  assert(label);
+  assert(state);
+
+  RenderText(string_data(label->text), string_length(label->text), state);
+}
+
+static void RenderTable(const uiTable* table, RenderState* state) {
+  assert(table);
+  assert(state);
+
+  const int x0 = state->pen.x;
+  const int y0 = state->pen.y;
+
+  uiRect  original_subsurface = {0};
+  uiPoint original_pen        = {0};
+
+  // Render header.
+  if (table->header) {
+    for (int col = 0; col < table->cols; ++col) {
+      // Crop the column contents to the column width so that one column does
+      // not spill into the next.
+      PushSubsurface(
+          state, table->widths[col], state->subsurface.height,
+          &original_subsurface, &original_pen);
+
+      const uiCell* cell = &table->header[col];
+      RenderWidget(state, cell->child);
+
+      // Reset the original subsurface and pen for subsequent columns.
+      PopSubsurface(state, &original_subsurface, &original_pen);
+
+      // Next column.
+      state->pen.x += table->widths[col];
+    }
+  }
+  state->pen.x = x0;
+  state->pen.y += g_ui.font->header.glyph_height;
+
+  // Render rows.
+  for (int row = 0; (row < table->rows) && PenInSurface(state, 0, 0); ++row) {
+    for (int col = 0; (col < table->cols) && PenInSurface(state, 0, 0); ++col) {
+      // Crop the column contents to the column width so that one column does
+      // not spill into the next.
+      PushSubsurface(
+          state, table->widths[col], state->subsurface.height,
+          &original_subsurface, &original_pen);
+
+      state->subsurface.x     = state->subsurface.x + state->pen.x;
+      state->subsurface.width = table->widths[col];
+      state->pen.x            = 0;
+
+      const uiCell* cell = GetCell(table, row, col);
+      RenderWidget(state, cell->child);
+
+      // Reset the original subsurface and pen for subsequent columns.
+      PopSubsurface(state, &original_subsurface, &original_pen);
+
+      // Next column.
+      state->pen.x += table->widths[col];
+    }
+    state->pen.x = x0;
+    state->pen.y += g_ui.font->header.glyph_height;
+  }
+  state->pen.y = y0;
+}
+
+static void RenderWidget(RenderState* state, const uiWidget* widget) {
+  assert(state);
+  assert(widget);
+
+  // Render this widget.
+  switch (widget->type) {
+  case uiTypeButton:
+    break;
+  case uiTypeFrame:
+    RenderFrame((const uiFrame*)widget, state);
+    break;
+  case uiTypeLabel:
+    RenderLabel((const uiLabel*)widget, state);
+    break;
+  case uiTypeTable:
+    RenderTable((const uiTable*)widget, state);
+    break;
+  case uiTypeMax:
+    TRAP();
+    break;
+  }
+
+  // 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);
+}