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matrix/include/graphics.h

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+// -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
+// Very simple graphics library to do simple things.
+//
+// Might be useful to consider using Cairo instead and just have an interface
+// between that and the Canvas. Well, this is a quick set of things to get
+// started (and nicely self-contained).
+#ifndef RPI_GRAPHICS_H
+#define RPI_GRAPHICS_H
+
+#include "canvas.h"
+
+#include <stdint.h>
+#include <stddef.h>
+
+#include <map>
+
+namespace rgb_matrix {
+struct Color {
+  Color() : r(0), g(0), b(0) {}
+  Color(uint8_t rr, uint8_t gg, uint8_t bb) : r(rr), g(gg), b(bb) {}
+  uint8_t r;
+  uint8_t g;
+  uint8_t b;
+};
+
+// Font loading bdf files. If this ever becomes more types, just make virtual
+// base class.
+class Font {
+public:
+  // Initialize font, but it is only usable after LoadFont() has been called.
+  Font();
+  ~Font();
+
+  bool LoadFont(const char *path);
+
+  // Return height of font in pixels. Returns -1 if font has not been loaded.
+  int height() const { return font_height_; }
+
+  // Return baseline. Pixels from the topline to the baseline.
+  int baseline() const { return base_line_; }
+
+  // Return width of given character, or -1 if font is not loaded or character
+  // does not exist.
+  int CharacterWidth(uint32_t unicode_codepoint) const;
+
+  // Draws the unicode character at position "x","y"
+  // with "color" on "background_color" (background_color can be NULL for
+  // transparency.
+  // The "y" position is the baseline of the font.
+  // If we don't have it in the font, draws the replacement character "<22>" if
+  // available.
+  // Returns how much we advance on the screen, which is the width of the
+  // character or 0 if we didn't draw any chracter.
+  int DrawGlyph(Canvas *c, int x, int y,
+                const Color &color, const Color *background_color,
+                uint32_t unicode_codepoint) const;
+
+  // Same without background. Deprecated, use the one above instead.
+  int DrawGlyph(Canvas *c, int x, int y, const Color &color,
+                uint32_t unicode_codepoint) const;
+
+  // Create a new font derived from this font, which represents an outline
+  // of the original font, essentially pixels tracing around the original
+  // letter.
+  // This can be used in situations in which it is desirable to frame a letter
+  // in a different color to increase contrast.
+  // The ownership of the returned pointer is passed to the caller.
+  Font *CreateOutlineFont() const;
+
+private:
+  Font(const Font& x);  // No copy constructor. Use references or pointer instead.
+
+  struct Glyph;
+  typedef std::map<uint32_t, Glyph*> CodepointGlyphMap;
+
+  const Glyph *FindGlyph(uint32_t codepoint) const;
+
+  int font_height_;
+  int base_line_;
+  CodepointGlyphMap glyphs_;
+};
+
+// -- Some utility functions.
+
+// Utility function: set an image from the given buffer containting pixels.
+//
+// Draw image of size "image_width" and "image_height" from pixel at
+// canvas-offset "canvas_offset_x", "canvas_offset_y". Image will be shown
+// cropped on the edges if needed.
+//
+// The canvas offset can be negative, i.e. the image start can be shifted
+// outside the image frame on the left/top edge.
+//
+// The buffer needs to be organized as rows with columns of three bytes
+// organized as rgb or bgr. Thus the size of the buffer needs to be exactly
+// (3 * image_width * image_height) bytes.
+//
+// The "image_buffer" parameters contains the data, "buffer_size_bytes" the
+// size in bytes.
+//
+// If "is_bgr" is true, the buffer is treated as BGR pixel arrangement instead
+// of RGB.
+// Returns 'true' if image was shown within canvas.
+bool SetImage(Canvas *c, int canvas_offset_x, int canvas_offset_y,
+              const uint8_t *image_buffer, size_t buffer_size_bytes,
+              int image_width, int image_height,
+              bool is_bgr);
+
+// Draw text, a standard NUL terminated C-string encoded in UTF-8,
+// with given "font" at "x","y" with "color".
+// "color" always needs to be set (hence it is a reference),
+// "background_color" is a pointer to optionally be NULL for transparency.
+// "kerning_offset" allows for additional spacing between characters (can be
+// negative)
+// Returns how many pixels we advanced on the screen.
+int DrawText(Canvas *c, const Font &font, int x, int y,
+             const Color &color, const Color *background_color,
+             const char *utf8_text, int kerning_offset = 0);
+
+// Same without background. Deprecated, use the one above instead.
+int DrawText(Canvas *c, const Font &font, int x, int y, const Color &color,
+             const char *utf8_text);
+
+// Draw text, a standard NUL terminated C-string encoded in UTF-8,
+// with given "font" at "x","y" with "color".
+// Draw text as above, but vertically (top down).
+// The text is a standard NUL terminated C-string encoded in UTF-8.
+// "font, "x", "y", "color" and "background_color" are same as DrawText().
+// "kerning_offset" allows for additional spacing between characters (can be
+// negative).
+// Returns font height to advance up on the screen.
+int VerticalDrawText(Canvas *c, const Font &font, int x, int y,
+                     const Color &color, const Color *background_color,
+                     const char *utf8_text, int kerning_offset = 0);
+
+// Draw a circle centered at "x", "y", with a radius of "radius" and with "color"
+void DrawCircle(Canvas *c, int x, int y, int radius, const Color &color);
+
+// Draw a line from "x0", "y0" to "x1", "y1" and with "color"
+void DrawLine(Canvas *c, int x0, int y0, int x1, int y1, const Color &color);
+
+}  // namespace rgb_matrix
+
+#endif  // RPI_GRAPHICS_H