Merge pull request #11 from pimoroni/examples/image-gallery

Add Image Gallery example

examples/image_gallery.py

@@ -0,0 +1,114 @@
+"""
+A gallery that shows all the .jpg and .png files saved to your Explorer.
+
+Use X and Y to cycle through images
+Z shows/hides the filename
+A and B change the background colour (for .png files with transparency)
+"""
+
+import os
+import jpegdec
+import pngdec
+from explorer import display, WHITE, BLACK, button_a, button_b, button_x, button_y, button_z
+import gc
+
+WIDTH, HEIGHT = display.get_bounds()
+
+TOTAL_IMAGES = 0
+
+jpeg = jpegdec.JPEG(display)
+png = pngdec.PNG(display)
+
+# Clear all layers first
+display.set_pen(BLACK)
+display.set_layer(0)
+display.clear()
+display.set_layer(1)
+display.clear()
+
+# Load images
+try:
+    IMAGES = [f for f in os.listdir("/") if f.endswith(".jpg") or f.endswith(".png")]
+    TOTAL_IMAGES = len(IMAGES)
+except OSError:
+    pass
+
+CURRENT_IMAGE = 0
+SHOW_INFO = True
+
+BACKGROUND = WHITE
+
+
+def show_image(n):
+    gc.collect()
+    file = IMAGES[n]
+    name, ext = file.split(".")
+
+    display.set_pen(BACKGROUND)
+    display.clear()
+
+    try:
+        png.open_file("/{}".format(file))
+        png.decode()
+    except (OSError, RuntimeError):
+        jpeg.open_file("/{}".format(file))
+        jpeg.decode()
+
+    if SHOW_INFO is True:
+        label = f"{name} ({ext})"
+        name_length = display.measure_text(label, 0.5)
+        display.set_pen(BLACK)
+        display.rectangle(0, HEIGHT - 21, name_length + 11, 21)
+        display.set_pen(WHITE)
+        display.rectangle(0, HEIGHT - 20, name_length + 10, 20)
+        display.set_pen(BLACK)
+        display.text(label, 5, HEIGHT - 10, WIDTH, 0.5)
+
+        for i in range(TOTAL_IMAGES):
+            x = WIDTH - 10
+            y = int((HEIGHT / 2) - (TOTAL_IMAGES * 10 / 2) + (i * 10))
+            display.set_pen(BLACK)
+            display.rectangle(x, y, 8, 8)
+            if CURRENT_IMAGE != i:
+                display.set_pen(WHITE)
+                display.rectangle(x + 1, y + 1, 6, 6)
+
+    display.update()
+
+
+changed = True
+
+if TOTAL_IMAGES == 0:
+    display.set_pen(BLACK)
+    display.clear()
+    display.set_pen(WHITE)
+    display.text("To run this demo, upload some .jpg or .png files to Explorer.", 0, 0, WIDTH, 3)
+    display.update()
+
+else:
+    while True:
+        if button_x.value() == 0:
+            if CURRENT_IMAGE > 0:
+                CURRENT_IMAGE -= 1
+                changed = True
+
+        if button_y.value() == 0:
+            if CURRENT_IMAGE < TOTAL_IMAGES - 1:
+                CURRENT_IMAGE += 1
+                changed = True
+
+        if button_a.value() == 0:
+            BACKGROUND = WHITE
+            changed = True
+
+        if button_b.value() == 0:
+            BACKGROUND = BLACK
+            changed = True
+
+        if button_z.value() == 0:
+            SHOW_INFO = not SHOW_INFO
+            changed = True
+
+        if changed:
+            show_image(CURRENT_IMAGE)
+            changed = False