Delphi.FMX.UImageCropper

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Delphi.FMX.UImageCropper

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A modern, mobile-oriented image cropper for Delphi FireMonkey (FMX) featuring auto-zoom, dynamic centered cropbox, and rendering powered by Skia4Delphi.

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# TUImageCropper

A modern, mobile-oriented image cropper for Delphi FireMonkey (FMX) featuring auto-zoom, dynamic centered cropbox, and rendering powered by [Skia4Delphi](https://github.com/skia4delphi/skia4delphi).

This is the modern standard for mobile devices because it enables precise crops, lockable aspect ratios, and clear visual feedback for all image areas, especially near the boundaries.

---

## ✨ Key Advantages

- **Fluid Touch Gestures:** Seamless control of the image (pan, zoom, and double tap). It also allows you to easily plug in custom visual controls for crop ratio, rotation, and mirroring.
- **Precise Visual Feedback:** The user always sees a well-defined crop area, while the dimming mask surrounding it clearly indicates which parts of the image will be discarded.
- **Flexible Cropping Grid:** The cropbox can be dynamically resized from both the corners and the edges.
- **Lockable Aspect Ratios:** Easily lock specific proportions (e.g., 1:1, 4:3, 16:9) or let the user resize it freely.
- **Smart Boundary Snapping:** The image is anchored to the cropbox. When a user selects an area close to the edges, the viewport smoothly disengages from the screen boundaries and centers itself within the cropbox for optimal visibility and precision.

Auto-Zoom Feature
 <img src="Images/cropper-1.gif"/>
 
 Manual Pinch-to-Zoom and Pan Feature
 <img src="Images/cropper-2.gif"/>

---

## ⚙️ Technical Features

- **Cross-Platform FMX:** Written in FMX (FireMonkey) and integrated with Skia4Delphi.
- **Flexible Integration:** Use it directly as source code within your project or install it into the Delphi Component Palette.
- **Wide Format Support:** Supports all image formats handled by the FMX Codec Manager (primarily JPG, PNG, BMP).
- **Asynchronous Operations:** Asynchronous image loading and cropping tasks prevent main UI thread blocks, keeping your application highly responsive.
- **Resource Efficient:** Saves memory by processing a lightweight sample/preview image in memory, while the original high-resolution file is safely managed in a cache file.
- **Highly Customizable:** Easily adapt its behavior, colors, and functionality through its built-in properties and events.

---

## 🚀 Getting Started

### Prerequisites

- Delphi 12/13 (FMX framework)
- Skia4Delphi installed and enabled in your project.

## Basic Usage

Follow these steps to integrate and use the `TUImageCropper` component in your FMX application:

1. **Create and initialize the component at runtime with Default Settings:**

```delphi
     
      uses
		 FMX.UICropperTypes,
		 FMX.UImageCropper;
         
      private 
		 FImageCropper: TUImageCropper;
         ...
	 begin
		 FImageCropper := TUImageCropper.Create(Self);
		 FImageCropper.Parent := CropperContainer; // Assign the visual container
		 FImageCropper.Align := TAlignLayout.Client;
   end;
	 ```

2. **Assign event handlers (Some are optional but recommended):**

```delphi
		 FImageCropper.OnImageLoad := OnImageLoadHandler;
		 FImageCropper.OnImageLoaded := OnImageLoadedHandler;
         FImageCropper.OnCropImage:= OnCropImageHandler;
         FImageCropper.OnImageCropped:= OnImageCroppedHandler;
		 FImageCropper.OnImageError := OnImageErrorHandler;
         FImageCropper.OnCropCancel:= OnCropCancelHandler;
	 ```

3. **Load an image from a TBitmap asynchronously:**

```delphi
		 FImageCropper.LoadImageFromBitmapAsync(Bitmap);
	 ```

**Notes:**
- You can load images from file using `LoadImageFromFileAsync('path/to/file.jpg')`.
- Use the event handlers to manage loading states, errors, and crop results.    
- Preview the image before cropping with `ShowCropPreview` and `CancelCropPreview`.
- The maximum size limit for a `TBitmap` in FMX is 8000x8000 (approximately 64MP).

## Example: Cropping an Image and Retrieving the Cropped File

This example demonstrates how to start the cropping operation, handle the crop completion event, and retrieve the cropped file path.

```delphi
procedure TForm1.StartCropping;
begin
	// Start the asynchronous cropping operation
	FImageCropper.CropImageAsync;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
	// Assign the event handler for when the image has been cropped
	FImageCropper.OnImageCropped := OnImageCroppedHandler;
end;

procedure TForm1.OnImageCroppedHandler(Sender: TObject);
var
	CroppedFileName: string;
begin
	// Try to get the cropped image file name
	if FImageCropper.TryGetCroppedImage(CroppedFileName) then
	begin
		ShowMessage('Cropped image saved at: ' + CroppedFileName);
		// You can now use the cropped file as needed
	end
	else
		ShowMessage('No cropped image available.');
end;
```
 
 **Notes:**
- To get the cropped image, use the `TryGetCroppedImage` method after cropping.
- Use the event handlers to manage loading states, errors, and crop results.

## Example: Profile Image Crop with Minimum and Maximum Size

This example shows how to configure a profile image crop with a square aspect ratio, minimum required image dimensions, and a maximum output size.

Suppose a profile picture is required with a minimum size of 256x256 and a maximum of 1024x1024. The adjustments are made accordingly.

```delphi
procedure TForm1.SetupProfileImageCrop;
begin
  // Require the source image to be at least 450x450 pixels
  FImageCropper.ImageSettings.MinReqWidth := 450;
  FImageCropper.ImageSettings.MinReqHeight := 450;

// Ensure the final cropped image is at least 256x256 pixels
  FImageCropper.MinPixelsWidth := 256;
  FImageCropper.MinPixelsHeight := 256;

// Use a square crop box for profile images
  FImageCropper.CropBoxSettings.AspectRatio := TUICropRatio.Square;

end;

procedure TForm1.CropProfileImage;
begin
  // Crop the image and limit the result to a maximum of 1024x1024 pixels
  FImageCropper.CropImageAsync(1024, 1024);
end;
```

**How it works:**
- `ImageSettings.MinReqWidth` and `ImageSettings.MinReqHeight` force a minimum source image size.
- `CropBoxSettings.AspectRatio := TUICropRatio.Square` keeps the crop box square for profile avatars.
- `MinPixelsWidth` and `MinPixelsHeight` guarantee the cropped result is not smaller than 256x256.
- `CropImageAsync(1024, 1024)` resizes the final cropped image to a maximum of 1024x1024.

## Example: Customizing Crop Box Colors and Borders

This example shows how to change the crop box border color and handle color using the `CropBoxSettings` property of `TUImageCropper`.

```delphi
procedure TForm1.CustomizeCropBox;
begin
	// Set the crop box border color
	FImageCropper.CropBoxSettings.Color := TAlphaColorRec.Red;

// Set the crop box handle color (corners)
	FImageCropper.CropBoxSettings.HandleColor := TAlphaColorRec.Blue;

// Set the crop box border thickness
	FImageCropper.CropBoxSettings.Thickness := 3.0;

// Set the crop box opacity
	FImageCropper.CropBoxSettings.Opacity := 0.8;
end;
```

**How it works:**
- Use the `CropBoxSettings.Color` property to change the border color of the crop box.
- Use the `CropBoxSettings.HandleColor` property to change the color of the corner handles.
- Adjust `Thickness` and `Opacity` for further customization of the crop box appearance.

## Methods

This table lists the main public methods of the `TUImageCropper` component.

| Method | Description |
|--------|-------------|
| `CancelCrop` | Cancels the current cropping operation and resets the viewport. |
| `CancelCropPreview` | Cancels the crop preview and returns to the main image view. |
| `ClearViewport` | It's the same as CancelCrop, but this method doesn't trigger the OnCropCancel event. |
| `CropImageAsync` | Starts the asynchronous cropping operation. |
| `CropImageAsync(const AWidth, AHeight: integer)` | Starts the asynchronous cropping operation and force the output image to be resampled when the image crop is larger than the specified dimensions.|
| `ShowCropPreview` | Displays a preview of the cropped area. |
| `LoadImageFromBitmapAsync(const ABitmap: TBitmap)` | Loads an image from a TBitmap asynchronously. |
| `LoadImageFromFileAsync(AFileName: string)` | Loads an image from a file asynchronously. |
| `MirrorImage` | Mirrors (flips horizontally) the current image. |
| `RotateImage90DegreesRight` | Rotates the image 90 degrees to the right (clockwise). |
| `RotateImage90DegreesLeft` | Rotates the image 90 degrees to the left (counterclockwise). |
| `TryGetCroppedImage(out FileName: string): Boolean` | Retrieves the filename of the cropped image if available. Returns true if successful. |
| `TryGetSourceImage(out FileName: string): Boolean` | Retrieves the filename of the source image if available. Returns true if successful. |

## Properties

This table describes the public and published properties of the `TUImageCropper` class, which configures the main Image Cropper component.

| Property              | Type                        | Description |
|-----------------------|-----------------------------|-------------|
| `IsImageZoomed`       | Boolean (read-only)         | Returns true if the image is currently zoomed in beyond its minimum scale. |
| `IsTouchZooming`      | Boolean (read-only)         | Returns true if a touch zoom gesture is currently active. |
| `IsImageRotated`      | Boolean (read-only)         | Returns true if the image has been rotated. |
| `IsMirroredImage`     | Boolean (read-only)         | Returns true if the image is currently mirrored horizontally. |
| `ImageScale`          | Single                      | The current scale (zoom level) of the image. |
| `ImageOffsetX`        | Single                      | The current horizontal offset of the image. |
| `ImageOffsetY`        | Single                      | The current vertical offset of the image. |
| `CropBoxCenterX`      | Single                      | The X coordinate of the crop box center. |
| `CropBoxCenterY`      | Single                      | The Y coordinate of the crop box center. |
| `CropBoxWidth`        | Single                      | The width of the crop box. |
| `CropBoxHeight`       | Single                      | The height of the crop box. |
| `ImageSample`         | ISkImage (read-only)        | The current image sample being displayed. |
| `BackgroundColor`     | TAlphaColor                 | The background color of the cropper viewport. |
| `CropBoxSettings`     | TUICropBoxSettings          | Crop box configuration (appearance, behavior, constraints). |
| `EnableBackground`    | Boolean                     | Enables or disables the background color. |
| `EnableAutoZoom`      | Boolean                     | Enables or disables auto-zoom when resizing the crop box. |
| `EnableElasticBounce` | Boolean                     | Enables or disables elastic bounce effect when panning the image out of bounds. |
| `EnableDoubleTap`     | Boolean                     | Enables or disables double-tap gesture for zooming. |
| `EnableMouseWheel`    | Boolean                     | Enables or disables zooming with the mouse wheel. |
| `EnablePinchZoom`     | Boolean                     | Enables or disables pinch-to-zoom gesture. |
| `EnableTouchPan`      | Boolean                     | Enables or disables touch panning of the image. |
| `ImageSettings`       | TUICropperImageSettings     | Image loading and saving settings. |
| `OverlaySettings`     | TUICropperOverlaySettings   | Overlay layer settings (appearance, effects). |
| `OnCropCancel`        | TNotifyEvent                | Event triggered when cropping is canceled. |
| `OnCropImage`         | TNotifyEvent                | Event triggered when cropping is initiated. |
| `OnImageCropped`      | TNotifyEvent                | Event triggered when the image has been cropped. |
| `OnImageError`        | TUIImageErrorEvent          | Event triggered when an image loading or cropping error occurs. |
| `OnImageLoad`         | TNotifyEvent                | Event triggered when image loading starts. |
| `OnImageLoaded`       | TNotifyEvent                | Event triggered when image loading is complete. |

**Notes:**
- Properties with type `TUICropBoxSettings`, `TUICropperImageSettings`, and `TUICropperOverlaySettings` refer to their respective configuration objects.
- Event properties allow you to handle user actions and errors in your application logic.
- Read-only properties provide runtime state information about the cropper and the image.

## TUICropBoxSettings API Reference

This table describes the properties of the `TUICropBoxSettings` class, which configures the CropBox behavior and appearance for an Image Cropper component.

| Property                   | Type         | Description |
|----------------------------|--------------|-------------|
| `AspectRatio`              | TUICropRatio | The aspect ratio of the crop box. |
| `AbsoluteOpacity`          | Single       | The absolute opacity of the crop box (0.0 to 1.0). |
| `AutoZoomThreshold`        | Single       | The auto-zoom trigger threshold, as a percentage of the viewport (e.g., 0.8 = 80%). |
| `Color`                    | TAlphaColor  | The color of the crop box border. |
| `CenteringTransitionDelay` | Single       | Delay in milliseconds before the crop box recenters after resizing. |
| `EnableEffects`            | Boolean      | Enables or disables crop box effects (e.g., fadeIn, transitions). |
| `EnableResizing`           | Boolean      | Enables or disables manual resizing of the crop box. |
| `GuidesThickness`          | Single       | Thickness of the guide lines (thirds grid) inside the crop box. |
| `GuideLinesOpacity`        | Single       | Opacity of the guide lines (thirds grid). |
| `GuideLinesFadeInDelay`    | Single       | Fade-in animation delay for the guide lines. |
| `GuideLinesFadeOutDelay`   | Single       | Fade-out animation delay for the guide lines. |
| `FadeInDelay`              | Single       | Fade-in animation delay for the crop box. |
| `FadeOutDelay`             | Single       | Fade-out animation delay for the crop box. |
| `HandleColor`              | TAlphaColor  | Color of the crop box handles (corners). |
| `HotHandleColor`           | TAlphaColor  | Color of the handle when touched (active). |
| `HotHandleThickness`       | Single       | Thickness of the handle when touched (active). |
| `HotEdgeThickness`         | Single       | Thickness of the crop box edge when touched. |
| `HandleGap`                | Single       | Gap between the handle and the crop box edge. |
| `HandleLength`             | Single       | Length of the crop box handles (corners). |
| `HandleOpacity`            | Single       | Opacity of the crop box handles. |
| `HandleThickness`          | Single       | Thickness of the crop box handles. |
| `HandleTolerance`          | Single       | Touch area (in px) around the handle for easier interaction. |
| `MinHeight`                | Integer      | Minimum height in px (screen only). |
| `MinPixelsHeight`          | Integer      | Minimum crop size(Height) in px of the original image. |
| `MinPixelsWidth`           | Integer      | Minimum crop size(Width) in px of the original image. |
| `MinWidth`                 | Integer      | Minimum width in px (screen only). |
| `SafeAreaMargin`           | Single       | Margin (in px) between the crop box and the viewport. |
| `Opacity`                  | Single       | Opacity of the crop box border. |
| `ShowGuideLines`           | Boolean      | Whether to show the guide lines (thirds grid) inside the crop box. |
| `Thickness`                | Single       | Thickness of the crop box border. |
| `TargetSizePercent`        | Single       | Target size factor (percentage) for the crop box within the viewport after auto-zoom and centering. |
| `Visible`                  | Boolean      | Whether the crop box is visible. |

## TUICropperOverlaySettings API Reference

This table describes the properties of the `TUICropperOverlaySettings` class, which configures the overlay layer for an Image Cropper component.

| Property         | Type         | Description |
|------------------|--------------|-------------|
| `Color`          | TAlphaColor  | The color of the overlay mask that dims the area outside the crop box. |
| `EnableEffects`  | Boolean      | Enables or disables overlay effects (such as fade animations). |
| `EnableOverlay`  | Boolean      | Enables or disables the overlay layer. |
| `MaxOpacity`     | Single       | Maximum opacity value for overlay animation interpolators (when overlay darkens dynamically on crop box touch). |
| `MinOpacity`     | Single       | Minimum opacity value for overlay animation interpolators (when overlay lightens dynamically on crop box touch). |
| `FadeInDelay`    | Single       | Fade-in animation delay for the overlay appearance. |
| `FadeOutDelay`   | Single       | Fade-out animation delay for the overlay disappearance. |
| `Opacity`        | Single       | The base opacity of the overlay mask (0.0 to 1.0). |

## TUICropperImageSettings API Reference

This table describes the properties of the `TUICropperImageSettings` class, which configures the image settings for an Image Cropper component.

| Property               | Type     | Description |
|------------------------|----------|-------------|
| `MaxAllowHeight`       | Integer  | Maximum allowed image height (in pixels) for loading into the cropper. |
| `MaxAllowWidth`        | Integer  | Maximum allowed image width (in pixels) for loading into the cropper. |
| `MegaPixelsLimit`      | Integer  | Maximum allowed image megapixels for loading into the cropper. |
| `MinReqHeight`         | Integer  | Minimum required image height (in pixels) to be accepted by the cropper. |
| `MinReqWidth`          | Integer  | Minimum required image width (in pixels) to be accepted by the cropper. |
| `SaveCompressQuality`  | Integer  | Compression quality (0-100) for saving the cropped image. Higher values mean better quality and larger file size. |
| `SaveCompressFormat`   | String   | File format for saving the cropped image (e.g., 'jpg', 'png'). |

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