From 9594f01a4d972dace5bf896a44ef943c67343da5 Mon Sep 17 00:00:00 2001
From: LongHairedHacker <sebastian@sebastians-site.de>
Date: Sun, 23 Sep 2018 21:34:23 +0200
Subject: [PATCH] First implementation of font renderer.

---
 src/main.rs         |  1 +
 src/st7735/fonts.rs | 99 +++++++++++++++++++++++++++++++++++++++++++++
 src/st7735/mod.rs   |  8 +++-
 3 files changed, 106 insertions(+), 2 deletions(-)
 create mode 100644 src/st7735/fonts.rs

diff --git a/src/main.rs b/src/main.rs
index ec97873..420989c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -28,6 +28,7 @@ mod logo;
 use printer::UsartPrinter;
 use st7735::gfx::{PrimitveGFX, GFX};
 use st7735::bitmaps::BitmapGFX;
+use st7735::fonts::FontRenderer;
 
 
 
diff --git a/src/st7735/fonts.rs b/src/st7735/fonts.rs
new file mode 100644
index 0000000..390abe3
--- /dev/null
+++ b/src/st7735/fonts.rs
@@ -0,0 +1,99 @@
+use st7735::gfx::PrimitveGFX;
+
+pub struct FontGlpyh {
+    pub bitmap_offset: usize, // Offset in glyph bitmap
+    pub width: u8, // Size of glyph
+    pub height: u8,
+    pub x_advance: u8, // Distance to advance along x-axis
+    pub x_offset: u8, // Distance to upper left coner from cursor pos
+    pub y_offset: u8,
+}
+
+
+pub struct Font {
+    pub bitmap: &'static [u8], // Glyph bitmaps, concatenated
+    pub glyphs: &'static [FontGlpyh], // Array of glyph metadata
+    pub first: u8, // Start of ASCII extend
+    pub last: u8, // End of ASCII extend
+    pub y_advance: u8, // Line height
+}
+
+
+pub trait FontRenderer: PrimitveGFX {
+    fn draw_glyph(&mut self, x: u8, y: u8, glyph: &FontGlpyh, font: &Font, size: u8, color: u16) {
+        if size == 0 {
+            return;
+        }
+
+        // Any clipping should be done by draw_rect
+
+        let x = x as i16;
+        let y = y as i16;
+        let size = size as i16;
+
+        let mut bo = glyph.bitmap_offset;
+        let mut set_pixels: i16 = 0;
+        let mut bits: u8 = 0;
+        let mut bit: u8 = 0;
+
+        for cur_y in 0..(glyph.height as i16) {
+            for cur_x in 0..(glyph.width as i16) {
+                if bit == 0 {
+                    bits = font.bitmap[bo];
+                    bo += 1;
+                    bit = 0x80;
+                }
+
+                if bit & bits != 0 {
+                    set_pixels += 1;
+                } else if set_pixels > 0 {
+                    let start_x = (x + ((glyph.x_offset as i16) + cur_x - set_pixels) * size) as u8;
+                    let start_y = (y + ((glyph.y_offset as i16) + cur_y) * size) as u8;
+                    let w = (set_pixels * size) as u8;
+                    let h = size as u8;
+                    self.fill_rect(start_x, start_y, w, h, color);
+
+                    set_pixels = 0;
+                }
+                bit >>= 1;
+            }
+
+            if set_pixels > 0 {
+                let start_x = (x +
+                               ((glyph.x_offset as i16) + (glyph.width as i16) -
+                                set_pixels) * size) as u8;
+                let start_y = (y + ((glyph.y_offset as i16) + cur_y) * size) as u8;
+                let w = (set_pixels * size) as u8;
+                let h = size as u8;
+                self.fill_rect(start_x, start_y, w, h, color);
+            }
+        }
+    }
+
+    fn draw_text(&mut self, x: u8, y: u8, text: &str, font: &Font, size: u8, color: u16) {
+        let mut cursor_x = x;
+        let mut cursor_y = y;
+
+        for text_char in text.chars() {
+            let c = if text_char.is_ascii() {
+                text_char as u8
+            }
+            else {
+                '?' as u8
+            };
+
+            if c == '\n' as u8 {
+                cursor_x = x;
+                cursor_y += font.y_advance * size;
+            }
+            else if c >= font.first && c <= font.last && c != '\r' as u8 {
+                let pos = (c - font.first) as usize;
+                let glyph = &font.glyphs[pos];
+                self.draw_glyph(cursor_x, cursor_y, glyph, &font, size, color);
+                cursor_x += glyph.x_advance * size;
+            }
+
+        }
+
+    }
+}
diff --git a/src/st7735/mod.rs b/src/st7735/mod.rs
index 4887744..7609e9e 100644
--- a/src/st7735/mod.rs
+++ b/src/st7735/mod.rs
@@ -9,6 +9,7 @@ mod commands;
 mod init;
 pub mod gfx;
 pub mod bitmaps;
+pub mod fonts;
 
 use st7735::commands::*;
 
@@ -591,6 +592,9 @@ impl<SPIAddr, GPIOAddr> bitmaps::BitmapGFX for St7735IO<SPIAddr, GPIOAddr>
         self.set_cs();
 
     }
-
-
 }
+
+
+impl<SPIAddr, GPIOAddr> fonts::FontRenderer for St7735IO<SPIAddr, GPIOAddr>
+    where SPIAddr: Location,
+            GPIOAddr: Location {}