Simple picture output

widgets/image_viewer_widget.py

@@ -0,0 +1,101 @@
+# in widgets/image_viewer_widget.py
+import dearpygui.dearpygui as dpg
+from .base_widget import BaseWidget
+import logging
+
+class ImageViewerWidget(BaseWidget):
+    """
+    Displays a zoomable image inside a plot. This definitive version implements
+    programmatic pan and zoom by handling mouse events manually and repeatedly
+    calling set_axis_limits, as this is the only reliable method to achieve
+    both an initial fit and subsequent user interaction.
+    """
+    def __init__(self, widget_type: str, config: dict, layout_manager, global_state):
+        super().__init__(widget_type, config, layout_manager, global_state)
+        
+        # Subscribe to the event that will provide new images
+        self.global_state.subscribe("NEW_IMAGE_CAPTURED", self.on_new_image)
+        
+        # Register for updates to handle the dirty flag and panning
+        layout_manager.updating_widgets.append("ImageViewerWidget")
+
+        # Initialize tags and state variables
+        self.texture_tag = None
+        self.image_draw_tag = None
+        self.last_image_size = (1, 1) # width, height
+        self.needs_fit = False # The "dirty flag" for deferred fitting
+
+    def create(self):
+        """Creates the DPG window, plot, and the necessary mouse handlers."""
+        if dpg.does_item_exist(self.window_tag): return
+        
+        with dpg.window(label="Image Viewer", tag=self.window_tag, on_close=self._on_window_close, width=800, height=600):
+            # The plot is our canvas. `equal_aspects` is critical for preventing distortion.
+            with dpg.plot(label="Image Plot", no_menus=True, height=-1, width=-1, equal_aspects=True) as self.plot_tag:
+                self.xaxis_tag = dpg.add_plot_axis(dpg.mvXAxis, no_tick_labels=True, no_gridlines=True)
+                self.yaxis_tag = dpg.add_plot_axis(dpg.mvYAxis, no_tick_labels=True, no_gridlines=True)
+
+    def on_new_image(self, image_path: str):
+        """Loads image data, deletes/recreates the drawing, and flags for a refit."""
+        if not image_path: return
+        logging.info(f"ImageViewer received new image: {image_path}")
+        try:
+            width, height, channels, data = dpg.load_image(image_path)
+            self.last_image_size = (width, height)
+            
+            # Create or update the texture in the registry
+            if self.texture_tag is not None:
+                dpg.delete_item(self.texture_tag)
+                
+            self.texture_tag = dpg.generate_uuid()
+            dpg.add_static_texture(width, height, data, tag=self.texture_tag, parent=self.layout_manager.texture_registry)
+
+            if self.image_draw_tag and dpg.does_item_exist(self.image_draw_tag):
+                dpg.delete_item(self.image_draw_tag)
+            
+            self.image_draw_tag = dpg.draw_image(self.texture_tag, (0, height), (width, 0), parent=self.plot_tag)
+            
+            # Set the dirty flag to trigger a fit on the next frame
+            self.needs_fit = True
+            
+            dpg.configure_item(self.window_tag, show=True)
+            dpg.configure_item(self.plot_tag, label=image_path)
+            dpg.focus_item(self.window_tag)
+
+        except Exception as e:
+            logging.error(f"ImageViewer failed to process image '{image_path}': {e}", exc_info=True)
+
+    def fit_image_to_plot(self):
+        """Calculates and MANUALLY sets the plot's axis limits for the initial fit."""
+        plot_width = dpg.get_item_width(self.window_tag)
+        plot_height = dpg.get_item_height(self.window_tag)
+        if plot_width <= 0 or plot_height <= 0: return
+
+        img_width, img_height = self.last_image_size
+        if img_width <= 0 or img_height <= 0: return
+
+        plot_aspect = plot_width / plot_height
+        img_aspect = img_width / img_height
+
+        if img_aspect > plot_aspect:
+            x_min, x_max = 0, img_width
+            required_y_span = img_width / plot_aspect
+            center_y = img_height / 2
+            y_min = center_y - required_y_span / 2
+            y_max = center_y + required_y_span / 2
+        else:
+            y_min, y_max = 0, img_height
+            required_x_span = img_height * plot_aspect
+            center_x = img_width / 2
+            x_min = center_x - required_x_span / 2
+            x_max = center_x + required_x_span / 2
+        
+        dpg.set_axis_limits(self.xaxis_tag, x_min, x_max)
+        dpg.set_axis_limits(self.yaxis_tag, y_min, y_max)
+
+    def update(self):
+        """On update, check if the image needs to be refit."""
+        if self.needs_fit:
+            if dpg.is_item_visible(self.plot_tag):
+                self.fit_image_to_plot()
+                self.needs_fit = False