1 files changed, 89 insertions, 0 deletions
diff --git a/preview.py b/preview.py
new file mode 100644
index 0000000..f22c6ba
--- /dev/null
+++ b/preview.py
@@ -0,0 +1,89 @@
+import subprocess
+import tempfile
+import threading
+from tkinter import *
+from tkinter import ttk
+
+from options import FFmpegOptions
+
+
+class PreviewPanel(ttk.LabelFrame):
+    def __init__(self, *args, get_ffmpeg_args=lambda: FFmpegOptions([], []), get_frame_count=lambda: 0, **kw):
+        super(PreviewPanel, self).__init__(*args, text='Preview', **kw)
+        self.input_path = None
+        self.get_ffmpeg_args = get_ffmpeg_args
+        self.get_frame_count = get_frame_count
+
+        def button(text, command, column):
+            ttk.Button(self, text=text, command=command).grid(column=column, row=0, sticky=(N, W, S, E))
+            self.columnconfigure(column, weight=1)
+
+        button("Preview Start", self.preview_start, 0)
+        button("Preview Middle", self.preview_middle, 1)
+        button("Preview End", self.preview_end, 2)
+
+        self.image = None
+        self.image_label = ttk.Label(self, anchor='center')
+        self.image_label.grid(column=0, row=1, columnspan=3, sticky=(N, W, S, E))
+        self.rowconfigure(1, weight=1)
+
+        self.enable(False)
+
+    def preview_at(self, offset):
+        offset = int(offset)
+        self.enable(False)
+        real_args = self.get_ffmpeg_args()
+        input_args = real_args.input
+        width = self.image_label.winfo_width()
+        height = self.image_label.winfo_height()
+        real_args.vf += [
+            rf'select=eq(n\,{offset})',
+            f'scale=w={width}:h={height}:force_original_aspect_ratio=decrease'
+        ]
+        real_args.output += ['-frames:v', '1']
+        output_args = real_args.output_with_vf()
+
+        def run():
+            _, output_path = tempfile.mkstemp(suffix='.png')
+            args = ['ffmpeg', '-hide_banner', '-v', 'warning', '-y'] + input_args + \
+                   ['-i', self.input_path] + output_args + [output_path]
+            print(args)
+            # noinspection PyArgumentList
+            proc = subprocess.Popen(args, stdin=subprocess.DEVNULL, stdout=subprocess.PIPE,
+                                    stderr=subprocess.STDOUT, text=True, creationflags=subprocess.CREATE_NO_WINDOW)
+            while proc.poll() is None:
+                out_data = proc.stdout.readline()
+                if out_data != '':
+                    print(out_data, end='')
+            self.enable(True)
+            self.image = PhotoImage(file=output_path)
+            self.image_label['image'] = self.image
+
+        threading.Thread(target=run).start()
+
+    def preview_start(self, *args):
+        self.preview_at(0)
+
+    def preview_middle(self, *args):
+        self.preview_at(self.get_frame_count() / 2)
+
+    def preview_end(self, *args):
+        self.preview_at(self.get_frame_count() - 1)
+
+    def enable(self, enabled):
+        state = 'disabled'
+        if enabled:
+            state = '!' + state
+        self.state([state])
+        for child in self.winfo_children():
+            try:
+                child.state([state])
+            except AttributeError:
+                pass
+
+    def set_input_path(self, path, data):
+        self.enable(data is not None)
+        if data is None:
+            self.input_path = None
+        else:
+            self.input_path = path