JUCE/modules/juce_graphics/images/juce_ImageFileFormat.h

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2013 - Raw Material Software Ltd.

   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3

   Details of these licenses can be found at: www.gnu.org/licenses

   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

   ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.juce.com for more information.

  ==============================================================================
*/

#ifndef __JUCE_IMAGEFILEFORMAT_JUCEHEADER__
#define __JUCE_IMAGEFILEFORMAT_JUCEHEADER__

#include "juce_Image.h"


//==============================================================================
/**
    Base-class for codecs that can read and write image file formats such
    as PNG, JPEG, etc.

    This class also contains static methods to make it easy to load images
    from files, streams or from memory.

    @see Image, ImageCache
*/
class JUCE_API  ImageFileFormat
{
protected:
    //==============================================================================
    /** Creates an ImageFormat. */
    ImageFileFormat()                   {}

public:
    /** Destructor. */
    virtual ~ImageFileFormat()          {}

    //==============================================================================
    /** Returns a description of this file format.

        E.g. "JPEG", "PNG"
    */
    virtual String getFormatName() = 0;

    /** Returns true if the given stream seems to contain data that this format understands.

        The format class should only read the first few bytes of the stream and sniff
        for header bytes that it understands.

        Note that this will advance the stream and leave it in a new position, so if you're
        planning on re-using it, you may want to rewind it after calling this method.

        @see decodeImage
    */
    virtual bool canUnderstand (InputStream& input) = 0;

    /** Returns true if this format uses the file extension of the given file. */
    virtual bool usesFileExtension (const File& possibleFile) = 0;

    /** Tries to decode and return an image from the given stream.

        This will be called for an image format after calling its canUnderStand() method
        to see if it can handle the stream.

        @param input    the stream to read the data from. The stream will be positioned
                        at the start of the image data (but this may not necessarily
                        be position 0)
        @returns        the image that was decoded, or an invalid image if it fails.
        @see loadFrom
    */
    virtual Image decodeImage (InputStream& input) = 0;

    //==============================================================================
    /** Attempts to write an image to a stream.

        To specify extra information like encoding quality, there will be appropriate parameters
        in the subclasses of the specific file types.

        @returns        true if it nothing went wrong.
    */
    virtual bool writeImageToStream (const Image& sourceImage,
                                     OutputStream& destStream) = 0;

    //==============================================================================
    /** Tries the built-in formats to see if it can find one to read this stream.
        There are currently built-in decoders for PNG, JPEG and GIF formats.
        The object that is returned should not be deleted by the caller.
        @see canUnderstand, decodeImage, loadFrom
    */
    static ImageFileFormat* findImageFormatForStream (InputStream& input);

    /** Looks for a format that can handle the given file extension.
        There are currently built-in formats for PNG, JPEG and GIF formats.
        The object that is returned should not be deleted by the caller.
    */
    static ImageFileFormat* findImageFormatForFileExtension (const File& file);

    //==============================================================================
    /** Tries to load an image from a stream.

        This will use the findImageFormatForStream() method to locate a suitable
        codec, and use that to load the image.

        @returns        the image that was decoded, or an invalid image if it fails.
    */
    static Image loadFrom (InputStream& input);

    /** Tries to load an image from a file.

        This will use the findImageFormatForStream() method to locate a suitable
        codec, and use that to load the image.

        @returns        the image that was decoded, or an invalid image if it fails.
    */
    static Image loadFrom (const File& file);

    /** Tries to load an image from a block of raw image data.

        This will use the findImageFormatForStream() method to locate a suitable
        codec, and use that to load the image.

        @returns        the image that was decoded, or an invalid image if it fails.
    */
    static Image loadFrom (const void* rawData,
                           size_t numBytesOfData);
};

//==============================================================================
/**
    A subclass of ImageFileFormat for reading and writing PNG files.

    @see ImageFileFormat, JPEGImageFormat
*/
class JUCE_API  PNGImageFormat  : public ImageFileFormat
{
public:
    //==============================================================================
    PNGImageFormat();
    ~PNGImageFormat();

    //==============================================================================
    String getFormatName() override;
    bool usesFileExtension (const File&) override;
    bool canUnderstand (InputStream&) override;
    Image decodeImage (InputStream&) override;
    bool writeImageToStream (const Image&, OutputStream&) override;
};


//==============================================================================
/**
    A subclass of ImageFileFormat for reading and writing JPEG files.

    @see ImageFileFormat, PNGImageFormat
*/
class JUCE_API  JPEGImageFormat  : public ImageFileFormat
{
public:
    //==============================================================================
    JPEGImageFormat();
    ~JPEGImageFormat();

    //==============================================================================
    /** Specifies the quality to be used when writing a JPEG file.

        @param newQuality  a value 0 to 1.0, where 0 is low quality, 1.0 is best, or
                           any negative value is "default" quality
    */
    void setQuality (float newQuality);

    //==============================================================================
    String getFormatName() override;
    bool usesFileExtension (const File&) override;
    bool canUnderstand (InputStream&) override;
    Image decodeImage (InputStream&) override;
    bool writeImageToStream (const Image&, OutputStream&) override;

private:
    float quality;
};

//==============================================================================
/**
    A subclass of ImageFileFormat for reading GIF files.

    @see ImageFileFormat, PNGImageFormat, JPEGImageFormat
*/
class JUCE_API  GIFImageFormat  : public ImageFileFormat
{
public:
    //==============================================================================
    GIFImageFormat();
    ~GIFImageFormat();

    //==============================================================================
    String getFormatName() override;
    bool usesFileExtension (const File&) override;
    bool canUnderstand (InputStream&) override;
    Image decodeImage (InputStream&) override;
    bool writeImageToStream (const Image&, OutputStream&) override;
};


#endif   // __JUCE_IMAGEFILEFORMAT_JUCEHEADER__