1 files changed, 93 insertions, 0 deletions
diff --git a/shared-module/displayio/OnDiskBitmap.c b/shared-module/displayio/OnDiskBitmap.c
new file mode 100644
index 000000000..6e4a4c6f0
--- /dev/null
+++ b/shared-module/displayio/OnDiskBitmap.c
@@ -0,0 +1,93 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "shared-bindings/displayio/OnDiskBitmap.h"
+
+#include <string.h>
+
+#include "py/mperrno.h"
+#include "py/runtime.h"
+
+static uint32_t read_word(uint16_t* bmp_header, uint16_t index) {
+    return bmp_header[index] | bmp_header[index + 1] << 16;
+}
+
+void common_hal_displayio_ondiskbitmap_construct(displayio_ondiskbitmap_t *self, pyb_file_obj_t* file) {
+    // Load the wave
+    self->file = file;
+    uint16_t bmp_header[24];
+    f_rewind(&self->file->fp);
+    UINT bytes_read;
+    if (f_read(&self->file->fp, bmp_header, 48, &bytes_read) != FR_OK) {
+        mp_raise_OSError(MP_EIO);
+    }
+    if (bytes_read != 48 ||
+        memcmp(bmp_header, "BM", 2) != 0) {
+        mp_raise_ValueError(translate("Invalid BMP file"));
+    }
+
+    // We can't cast because we're not aligned.
+    self->data_offset = read_word(bmp_header, 5);
+
+    uint32_t header_size = read_word(bmp_header, 7);
+    uint32_t compression = read_word(bmp_header, 15);
+    if (!(header_size == 12 || header_size == 40 || header_size == 108 || header_size == 124) ||
+        !(compression == 0)) {
+        mp_raise_ValueError_varg(translate("Only Windows format, uncompressed BMP supported %d"), header_size);
+    }
+    // TODO(tannewt): Support bitfield compressed colors since RGB565 can be produced by the GIMP.
+    uint16_t bits_per_pixel = bmp_header[14];
+    if (bits_per_pixel < 24) {
+        mp_raise_ValueError_varg(translate("Only true color (24 bpp or higher) BMP supported %x"), bits_per_pixel);
+    }
+    self->bytes_per_pixel = bits_per_pixel / 8;
+    self->width = read_word(bmp_header, 9);
+    self->height = read_word(bmp_header, 11);
+    uint32_t byte_width = self->width * self->bytes_per_pixel;
+    self->stride = byte_width;
+    // Rows are word aligned.
+    if (self->stride % 4 != 0) {
+        self->stride += 4 - self->stride % 4;
+    }
+}
+
+
+uint32_t common_hal_displayio_ondiskbitmap_get_pixel(displayio_ondiskbitmap_t *self,
+        int16_t x, int16_t y) {
+    if (x < 0 || x >= self->width || y < 0 || y >= self->height) {
+        return 0;
+    }
+    uint32_t location = self->data_offset + (self->height - y) * self->stride + x * self->bytes_per_pixel;
+    // We don't cache here because the underlying FS caches sectors.
+    f_lseek(&self->file->fp, location);
+    UINT bytes_read;
+    uint32_t pixel = 0;
+    uint32_t result = f_read(&self->file->fp, &pixel, self->bytes_per_pixel, &bytes_read);
+    if (result == FR_OK) {
+        return pixel;
+    }
+    return 0;
+}