feat(freetype): add freetype example

freetype/examples/freetype-example/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.17)
+
+set(COMPONENTS main)
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(freetype-example)

freetype/examples/freetype-example/README.md

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+# FreeType Example
+
+This is a simple example of initializing FreeType library, loading a font from a filesystem, and rendering a line of text.
+
+The font file (DejaVu Sans) is downloaded at compile time and is added into a SPIFFS filesystem image. The filesystem is flashed to the board together with the application. The example loads the font file and renders "FreeType" text into the console as ASCII art.
+
+This example doesn't require any special hardware and can run on any development board.
+
+## Building and running
+
+Run the application as usual for an ESP-IDF project. For example, for ESP32:
+```
+idf.py set-target esp32
+idf.py -p PORT flash monitor
+```
+
+## Example output
+
+The example should output the following:
+
+```
+I (468) main_task: Calling app_main()
+I (538) example: FreeType library initialized
+I (1258) example: Font loaded
+I (1268) example: Rendering char: 'F'
+I (1388) example: Rendering char: 'r'
+I (1528) example: Rendering char: 'e'
+I (1658) example: Rendering char: 'e'
+I (1798) example: Rendering char: 'T'
+I (1938) example: Rendering char: 'y'
+I (2078) example: Rendering char: 'p'
+I (2208) example: Rendering char: 'e'
+
+
+######.                          #########
+##                                  +#
+##      #####   +###+    +###+      +#   +#    ########     +###+
+##      ##+    +#. .#+  +#. .#+     +#    #+   #+##+ .#+   +#. .#+
+######  ##     #+   +#  #+   +#     +#    ##  +# ##   +#   #+   +#
+##      ##    .####### .#######     +#    .#  ## ##   .#  .#######
+##      ##    .#.      .#.          +#     #+.#. ##   .#  .#.
+##      ##     #+       #+          +#     +###  ##   +#   #+
+##      ##     ##+  ++  ##+  ++     +#      ##+  ##+ .#+   ##+  ++
+##      ##      +####    +####      +#      ##   ######     +####
+                                            ##   ##
+                                           +#.   ##
+                                          ##+    ##
+
+
+
+```

freetype/examples/freetype-example/main/CMakeLists.txt

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+idf_component_register(SRCS "freetype-example.c"
+                    INCLUDE_DIRS "."
+                    PRIV_REQUIRES spiffs)
+
+# Download the example font into a directory "spiffs" in the build directory
+set(URL "https://github.com/espressif/esp-docs/raw/f036a337d8bee5d1a93b2264ecd29255baec4260/src/esp_docs/fonts/DejaVuSans.ttf")
+set(FILE "DejaVuSans.ttf")
+set(SPIFFS_DIR "${CMAKE_BINARY_DIR}/spiffs")
+file(MAKE_DIRECTORY ${SPIFFS_DIR})
+file(DOWNLOAD ${URL} ${SPIFFS_DIR}/${FILE} SHOW_PROGRESS)
+
+# Create a partition named "fonts" with the example font
+spiffs_create_partition_image(fonts ${SPIFFS_DIR} FLASH_IN_PROJECT)

freetype/examples/freetype-example/main/freetype-example.c

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+/*
+ * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: CC0-1.0
+ */
+
+
+#include <stdlib.h>
+#include "esp_log.h"
+#include "esp_err.h"
+#include "esp_spiffs.h"
+#include "ft2build.h"
+#include FT_FREETYPE_H
+
+static const char *TAG = "example";
+
+static void init_filesystem(void);
+static void init_freetype(void);
+static void load_font(void);
+static void render_text(void);
+
+#define BITMAP_WIDTH  80
+#define BITMAP_HEIGHT 18
+
+static FT_Library  s_library;
+static FT_Face s_face;
+static uint8_t s_bitmap[BITMAP_HEIGHT][BITMAP_WIDTH];
+
+
+void app_main(void)
+{
+    init_filesystem();
+    init_freetype();
+    load_font();
+    render_text();
+}
+
+static void init_filesystem(void)
+{
+    esp_vfs_spiffs_conf_t conf = {
+        .base_path = "/fonts",
+        .partition_label = "fonts",
+        .max_files = 1,
+    };
+
+    ESP_ERROR_CHECK(esp_vfs_spiffs_register(&conf));
+}
+
+static void init_freetype(void)
+{
+    FT_Error error = FT_Init_FreeType( &s_library );
+    if (error) {
+        ESP_LOGE(TAG, "Error initializing FreeType library: %d", error);
+        abort();
+    }
+
+    ESP_LOGI(TAG, "FreeType library initialized");
+}
+
+static void load_font(void)
+{
+    FT_Error error = FT_New_Face( s_library,
+                                  "/fonts/DejaVuSans.ttf",
+                                  0,
+                                  &s_face );
+    if (error) {
+        ESP_LOGE(TAG, "Error loading font: %d", error);
+        abort();
+    }
+
+    ESP_LOGI(TAG, "Font loaded");
+
+}
+
+static void render_text(void)
+{
+    /* Configure character size. */
+    const int font_size = 14;
+    const int freetype_scale = 64;
+    FT_Error error = FT_Set_Char_Size(s_face, 0, font_size * freetype_scale, 0, 0 );
+    if (error) {
+        ESP_LOGE(TAG, "Error setting font size: %d", error);
+        abort();
+    }
+
+    const char *text = "FreeType";
+    int num_chars = strlen(text);
+
+    /* current drawing position */
+    int x = 0;
+    int y = 12;
+
+    for (int n = 0; n < num_chars; n++) {
+        ESP_LOGI(TAG, "Rendering char: '%c'", text[n]);
+
+        /* retrieve glyph index from character code */
+        FT_UInt  glyph_index = FT_Get_Char_Index( s_face, text[n] );
+
+        /* load glyph image into the slot (erase previous one) */
+        error = FT_Load_Glyph( s_face, glyph_index, FT_LOAD_DEFAULT );
+        if (error) {
+            ESP_LOGE(TAG, "Error loading glyph: %d", error);
+            abort();
+        }
+
+        /* convert to a bitmap */
+        error = FT_Render_Glyph( s_face->glyph, FT_RENDER_MODE_NORMAL );
+        if (error) {
+            ESP_LOGE(TAG, "Error rendering glyph: %d", error);
+            abort();
+        }
+
+        /* copy the glyph bitmap into the overall bitmap */
+        FT_GlyphSlot slot = s_face->glyph;
+        for (int iy = 0; iy < slot->bitmap.rows; iy++) {
+            for (int ix = 0; ix < slot->bitmap.width; ix++) {
+                /* bounds check */
+                int res_x = ix + x;
+                int res_y = y + iy - slot->bitmap_top;
+                if (res_x >= BITMAP_WIDTH || res_y >= BITMAP_HEIGHT) {
+                    continue;
+                }
+                s_bitmap[res_y][res_x] = slot->bitmap.buffer[ix + iy * slot->bitmap.width];
+            }
+        }
+
+        /* increment horizontal position */
+        x += slot->advance.x / 64;
+        if (x >= BITMAP_WIDTH) {
+            break;
+        }
+    }
+
+    /* output the resulting bitmap to console */
+    for (int iy = 0; iy < BITMAP_HEIGHT; iy++) {
+        for (int ix = 0; ix < x; ix++) {
+            int val = s_bitmap[iy][ix];
+            if (val > 127) {
+                putchar('#');
+            } else if (val > 64) {
+                putchar('+');
+            } else if (val > 32) {
+                putchar('.');
+            } else {
+                putchar(' ');
+            }
+        }
+        putchar('\n');
+    }
+}

freetype/examples/freetype-example/main/idf_component.yml

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+dependencies:
+  espressif/freetype:
+    version: "*"
+    override_path: "../../.."

freetype/examples/freetype-example/partitions.csv

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+nvs,      data, nvs,     0x9000,  0x6000,
+phy_init, data, phy,     0xf000,  0x1000,
+factory,  app,  factory, 0x10000, 1M,
+fonts,    data, spiffs,  ,        0xF0000,

freetype/examples/freetype-example/sdkconfig.defaults

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+CONFIG_PARTITION_TABLE_CUSTOM=y
+CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions.csv"
+
+CONFIG_ESP_MAIN_TASK_STACK_SIZE=20000
+CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK=y