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</pre><div class="example-wrap"><pre class="rust ">
<span class="kw">use</span> <span class="ident">byteorder</span>::{<span class="ident">LittleEndian</span>, <span class="ident">ReadBytesExt</span>};
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">default</span>::<span class="ident">Default</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">io</span>::{<span class="ident">Cursor</span>, <span class="ident">Read</span>};
<span class="kw">use</span> <span class="ident">image</span>;
<span class="kw">use</span> <span class="ident">image</span>::<span class="ident">ImageDecoder</span>;
<span class="kw">use</span> <span class="ident">image</span>::<span class="ident">ImageResult</span>;
<span class="kw">use</span> <span class="ident">color</span>;
<span class="kw">use</span> <span class="kw">super</span>::<span class="ident">vp8</span>::<span class="ident">Frame</span>;
<span class="kw">use</span> <span class="kw">super</span>::<span class="ident">vp8</span>::<span class="ident">VP8Decoder</span>;
<span class="doccomment">/// Webp Image format decoder. Currently only supportes the luma channel (meaning that decoded</span>
<span class="doccomment">/// images will be grayscale).</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">WebpDecoder</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="ident">r</span>: <span class="ident">R</span>,
<span class="ident">frame</span>: <span class="ident">Frame</span>,
<span class="ident">have_frame</span>: <span class="ident">bool</span>,
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Read</span><span class="op">></span> <span class="ident">WebpDecoder</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="doccomment">/// Create a new WebpDecoder from the Reader ```r```.</span>
<span class="doccomment">/// This function takes ownership of the Reader.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">r</span>: <span class="ident">R</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ImageResult</span><span class="op"><</span><span class="ident">WebpDecoder</span><span class="op"><</span><span class="ident">R</span><span class="op">></span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">f</span>: <span class="ident">Frame</span> <span class="op">=</span> <span class="ident">Default</span>::<span class="ident">default</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">decoder</span> <span class="op">=</span> <span class="ident">WebpDecoder</span> {
<span class="ident">r</span>,
<span class="ident">have_frame</span>: <span class="bool-val">false</span>,
<span class="ident">frame</span>: <span class="ident">f</span>,
};
<span class="ident">decoder</span>.<span class="ident">read_metadata</span>()<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>(<span class="ident">decoder</span>)
}
<span class="kw">fn</span> <span class="ident">read_riff_header</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ImageResult</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">riff</span> <span class="op">=</span> <span class="ident">Vec</span>::<span class="ident">with_capacity</span>(<span class="number">4</span>);
<span class="macro">try</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">r</span>.<span class="ident">by_ref</span>().<span class="ident">take</span>(<span class="number">4</span>).<span class="ident">read_to_end</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">riff</span>));
<span class="kw">let</span> <span class="ident">size</span> <span class="op">=</span> <span class="macro">try</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">r</span>.<span class="ident">read_u32</span>::<span class="op"><</span><span class="ident">LittleEndian</span><span class="op">></span>());
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">webp</span> <span class="op">=</span> <span class="ident">Vec</span>::<span class="ident">with_capacity</span>(<span class="number">4</span>);
<span class="macro">try</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">r</span>.<span class="ident">by_ref</span>().<span class="ident">take</span>(<span class="number">4</span>).<span class="ident">read_to_end</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">webp</span>));
<span class="kw">if</span> <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">riff</span> <span class="op">!</span><span class="op">=</span> <span class="string">b"RIFF"</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">image</span>::<span class="ident">ImageError</span>::<span class="ident">FormatError</span>(
<span class="string">"Invalid RIFF signature."</span>.<span class="ident">to_string</span>(),
));
}
<span class="kw">if</span> <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">webp</span> <span class="op">!</span><span class="op">=</span> <span class="string">b"WEBP"</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">image</span>::<span class="ident">ImageError</span>::<span class="ident">FormatError</span>(
<span class="string">"Invalid WEBP signature."</span>.<span class="ident">to_string</span>(),
));
}
<span class="prelude-val">Ok</span>(<span class="ident">size</span>)
}
<span class="kw">fn</span> <span class="ident">read_vp8_header</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ImageResult</span><span class="op"><</span>()<span class="op">></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">vp8</span> <span class="op">=</span> <span class="ident">Vec</span>::<span class="ident">with_capacity</span>(<span class="number">4</span>);
<span class="macro">try</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">r</span>.<span class="ident">by_ref</span>().<span class="ident">take</span>(<span class="number">4</span>).<span class="ident">read_to_end</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">vp8</span>));
<span class="kw">if</span> <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">vp8</span> <span class="op">!</span><span class="op">=</span> <span class="string">b"VP8 "</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">image</span>::<span class="ident">ImageError</span>::<span class="ident">FormatError</span>(
<span class="string">"Invalid VP8 signature."</span>.<span class="ident">to_string</span>(),
));
}
<span class="kw">let</span> <span class="ident">_len</span> <span class="op">=</span> <span class="macro">try</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">r</span>.<span class="ident">read_u32</span>::<span class="op"><</span><span class="ident">LittleEndian</span><span class="op">></span>());
<span class="prelude-val">Ok</span>(())
}
<span class="kw">fn</span> <span class="ident">read_frame</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ImageResult</span><span class="op"><</span>()<span class="op">></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">framedata</span> <span class="op">=</span> <span class="ident">Vec</span>::<span class="ident">new</span>();
<span class="macro">try</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">r</span>.<span class="ident">read_to_end</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">framedata</span>));
<span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">io</span>::<span class="ident">Cursor</span>::<span class="ident">new</span>(<span class="ident">framedata</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">v</span> <span class="op">=</span> <span class="ident">VP8Decoder</span>::<span class="ident">new</span>(<span class="ident">m</span>);
<span class="kw">let</span> <span class="ident">frame</span> <span class="op">=</span> <span class="macro">try</span><span class="macro">!</span>(<span class="ident">v</span>.<span class="ident">decode_frame</span>());
<span class="self">self</span>.<span class="ident">frame</span> <span class="op">=</span> <span class="ident">frame</span>.<span class="ident">clone</span>();
<span class="prelude-val">Ok</span>(())
}
<span class="kw">fn</span> <span class="ident">read_metadata</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ImageResult</span><span class="op"><</span>()<span class="op">></span> {
<span class="kw">if</span> <span class="op">!</span><span class="self">self</span>.<span class="ident">have_frame</span> {
<span class="macro">try</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">read_riff_header</span>());
<span class="macro">try</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">read_vp8_header</span>());
<span class="macro">try</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">read_frame</span>());
<span class="self">self</span>.<span class="ident">have_frame</span> <span class="op">=</span> <span class="bool-val">true</span>;
}
<span class="prelude-val">Ok</span>(())
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Read</span><span class="op">></span> <span class="ident">ImageDecoder</span> <span class="kw">for</span> <span class="ident">WebpDecoder</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Reader</span> <span class="op">=</span> <span class="ident">Cursor</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span>;
<span class="kw">fn</span> <span class="ident">dimensions</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> (<span class="ident">u64</span>, <span class="ident">u64</span>) {
(<span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">u64</span>, <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">height</span> <span class="kw">as</span> <span class="ident">u64</span>)
}
<span class="kw">fn</span> <span class="ident">colortype</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">color</span>::<span class="ident">ColorType</span> {
<span class="ident">color</span>::<span class="ident">ColorType</span>::<span class="ident">Gray</span>(<span class="number">8</span>)
}
<span class="kw">fn</span> <span class="ident">into_reader</span>(<span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ImageResult</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Reader</span><span class="op">></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Cursor</span>::<span class="ident">new</span>(<span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">ybuf</span>))
}
<span class="kw">fn</span> <span class="ident">read_image</span>(<span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">ImageResult</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span> {
<span class="prelude-val">Ok</span>(<span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">ybuf</span>)
}
}
</pre></div>
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