Add an image viewer application

Author: jepler

examples/viewer/code.py

@@ -0,0 +1,153 @@
+# SPDX-FileCopyrightText: 2024 Jeff Epler for Adafruit Industries
+#
+# SPDX-License-Identifier: Unlicense
+
+"""Image viewer
+
+This will display all *jpeg* format images on the inserted SD card.
+
+Press up or down to move by +- 10 images.
+Press left or right to move by +- 1 image.
+
+Otherwise, images cycle every DISPLAY_INTERVAL milliseconds (default 8000 = 8 seconds)
+"""
+
+import time
+import os
+import displayio
+from jpegio import JpegDecoder
+from adafruit_ticks import ticks_less, ticks_ms, ticks_add, ticks_diff
+from adafruit_pycamera import PyCameraBase
+
+DISPLAY_INTERVAL = 8000  # milliseconds
+
+decoder = JpegDecoder()
+
+pycam = PyCameraBase()
+pycam.init_display()
+
+
+def load_resized_image(bitmap, filename):
+    print(f"loading {filename}")
+    bitmap.fill(0b01000_010000_01000)  # fill with a middle grey
+
+    bw, bh = bitmap.width, bitmap.height
+    t0 = ticks_ms()
+    h, w = decoder.open(filename)
+    t1 = ticks_ms()
+    print(f"{ticks_diff(t1, t0)}ms to open")
+    scale = 0
+    print(f"Full image size is {w}x{h}")
+    print(f"Bitmap is {bw}x{bh} pixels")
+    while (w >> scale) > bw or (h >> scale) > bh and scale < 3:
+        scale += 1
+    sw = w >> scale
+    sh = h >> scale
+    print(f"will load at {scale=}, giving {sw}x{sh} pixels")
+
+    if sw > bw:  # left/right sides cut off
+        x = 0
+        x1 = (sw - bw) // 2
+    else:  # horizontally centered
+        x = (bw - sw) // 2
+        x1 = 0
+
+    if sh > bh:  # top/bottom sides cut off
+        y = 0
+        y1 = (sh - bh) // 2
+    else:  # vertically centered
+        y = (bh - sh) // 2
+        y1 = 0
+
+    print(f"{x=} {y=} {x1=} {y1=}")
+    decoder.decode(bitmap, x=x, y=y, x1=x1, y1=y1, scale=scale)
+    t1 = ticks_ms()
+    print(f"{ticks_diff(t1, t0)}ms to decode")
+
+
+def mount_sd():
+    if not pycam.card_detect.value:
+        pycam.display_message("No SD card\ninserted", color=0xFF0000)
+        return []
+    pycam.display_message("Mounting\nSD Card", color=0xFFFFFF)
+    for _ in range(3):
+        try:
+            print("Mounting card")
+            pycam.mount_sd_card()
+            print("Success!")
+            break
+        except OSError as e:
+            print("Retrying!", e)
+            time.sleep(0.5)
+    else:
+        pycam.display_message("SD Card\nFailed!", color=0xFF0000)
+        time.sleep(0.5)
+    all_images = [
+        f"/sd/{filename}"
+        for filename in os.listdir("/sd")
+        if filename.lower().endswith(".jpg")
+    ]
+    pycam.display_message(f"Found {len(all_images)}\nimages", color=0xFFFFFF)
+    time.sleep(0.5)
+    pycam.display.refresh()
+    return all_images
+
+
+def main():
+    image_counter = 0
+    last_image_counter = 0
+    deadline = ticks_ms()
+    all_images = mount_sd()
+
+    bitmap = displayio.Bitmap(pycam.display.width, pycam.display.height, 65535)
+
+    while True:
+        pycam.keys_debounce()
+        if pycam.card_detect.fell:
+            print("SD card removed")
+            pycam.unmount_sd_card()
+            pycam.display_message("SD Card\nRemoved", color=0xFFFFFF)
+            time.sleep(0.5)
+            pycam.display.refresh()
+            all_images = []
+
+        now = ticks_ms()
+        if pycam.card_detect.rose:
+            print("SD card inserted")
+            all_images = mount_sd()
+            image_counter = 0
+            deadline = now
+
+        if all_images:
+            if pycam.up.fell:
+                image_counter = (last_image_counter - 10) % len(all_images)
+                deadline = now
+
+            if pycam.down.fell:
+                image_counter = (last_image_counter + 10) % len(all_images)
+                deadline = now
+
+            if pycam.left.fell:
+                image_counter = (last_image_counter - 1) % len(all_images)
+                deadline = now
+
+            if pycam.right.fell:
+                image_counter = (last_image_counter + 1) % len(all_images)
+                deadline = now
+
+            if ticks_less(deadline, now):
+                print(now, deadline, ticks_less(deadline, now), all_images)
+                deadline = ticks_add(deadline, DISPLAY_INTERVAL)
+                filename = all_images[image_counter]
+                last_image_counter = image_counter
+                image_counter = (image_counter + 1) % len(all_images)
+                try:
+                    load_resized_image(bitmap, filename)
+                except Exception as e:  # pylint: disable=broad-exception-caught
+                    pycam.display_message(f"Failed to read\n{filename}", color=0xFF0000)
+                    print(e)
+                    deadline = ticks_add(now, 500)
+                pycam.blit(bitmap, y_offset=0)
+
+
+main()