README

delphi-webp

Library for encoding and decoding Webp images in Delphi.

The library also provides a VCL component for rendering images in VCL applications.

Based on Delphi Unit by Henri Gourvest

Provides API and helper functions to use libwebp by Google

Usage

You need to download or compile the latest libwebp dynamic link library to use this library. See BUILDING.md for build instructions. Alternatively, you may use the included precompiled libraries in bin\, note however this requires Visual C++ Redistributable for Visual Studio 2015.

You can use the libwebp.pas unit to interact directly with the libwebp API, documentation for the API is available at https://developers.google.com/speed/webp/docs/api or you can use the WebpHelpers.pas unit which provide easy to use helper functions which wrap around the API. See below for documentation regarding the helpers.

WebHelpers unit

This library provides some basic helper functions for encoding and decoding Webp formatted images.

Encoding

There are two helpers for encoding images to Webp: WebpEncode and WebpLosslessEncode

These procedure allows you to encode images from other formats to Webp easily using the Windows API's GDI+ bitmap object and libwebp.

The procedures takes a TGPBitmap as input and outputs the resulting Webp image buffer to a stream or byte array.

See example usage below:

var 
    bmp : TGPBitmap;
    ms : TMemoryStream;
begin
    ms := TMemoryStream.Create;
    bmp := TGPBitmap.Create('image.png');
    // params are 
    // 1. stream to write to
    // 2. bitmap object containing the image data
    // 3. Quality factor from 0 to 100
    WebpEncode(ms, bmp, 100);
    // WebpLosslessEncode(ms, bmp); // Lossless webp encode.
    // save the webp image to a file
    ms.SaveToFile('out.webp');
    // Remember to free the objects after use
    bmp.free;
    ms.free;
end.

Decoding

There is a helper called WebpDecode to help with decoding Webp images and load it into a TGPBitmap object.

It takes a file stream as input and outputs the decoded image data buffer and bitmap object.

See usage example below:

var
    fs : TFileStream;
    bmp : TGPBitmap;
    dat : PByte;
begin
    fs := TFileStream.Create('input.webp', fmOpenRead);
    WebpDecode(fs, dat, bmp);
    bmp.Save('decoded.png', gPNG);
    // Free the memory
    bmp.Free;
    fs.Free;
    // Free the buffer. You must use this function as the buffer must be free'd by the libwebp dll.
    WebPFree(dat);
end.

VCL TWebpImage in Vcl.WebpImage unit

Control for displaying Webp images based on TGraphicControl. Coded to be easy to use.

See example below or in file examples\display_vcl

var
  img : TWebpImage;
begin
  img := TWebpImage.Create(self);
  img.Parent := self;
  img.Align := alClient;
  img.Stretch := true;
  img.Proportional := true;
  img.Center := true; // center image in canvas.
  // img.Offset := Point(10, 10); // offset the image on the canvas.
  // img.Scale := 1.5; // upscale the image. Great for making a image viewer.
  img.LoadFromFile('image.webp');
  // img.LoadFromStream(stream); // Load image from TStream or decendant
end.

License

This code is licensed under the same terms as WebM:

Software License Agreement: http://www.webmproject.org/license/software/

Additional IP Rights Grant: http://www.webmproject.org/license/additional/