fix sprites for pixel ratios that are not 1 and 2

- OpenGL ES 2 doesn't allow NPOT textures with wrap-around
- The Sprite object reported the map's pixelRatio, even though it loaded @2x assets
- Copying icons from the sprite into the atlas now uses bilinear scaling to scale up to the actual size

1 files changed, 96 insertions, 0 deletions

diff --git a/src/mbgl/util/compression.cpp b/src/mbgl/util/compression.cpp
new file mode 100644
index 0000000000..3a1658b8f6
--- /dev/null
+++ b/src/mbgl/util/compression.cpp
@@ -0,0 +1,96 @@
+#include "compression.hpp"
+
+#include <zlib.h>
+
+#include <cstring>
+#include <stdexcept>
+
+
+// Check zlib library version.
+const static bool zlibVersionCheck = []() {
+    const char *const version = zlibVersion();
+    if (version[0] != ZLIB_VERSION[0]) {
+        char message[96];
+        snprintf(message, 96, "zlib version mismatch: headers report %s, but library reports %s",
+                 ZLIB_VERSION, version);
+        throw std::runtime_error(message);
+    }
+
+    return true;
+}();
+
+
+namespace mbgl {
+namespace util {
+
+std::string compress(const std::string &raw) {
+    z_stream deflate_stream;
+    memset(&deflate_stream, 0, sizeof(deflate_stream));
+
+    // TODO: reuse z_streams
+    if (deflateInit(&deflate_stream, Z_DEFAULT_COMPRESSION) != Z_OK) {
+        throw std::runtime_error("failed to initialize deflate");
+    }
+
+    deflate_stream.next_in = (Bytef *)raw.data();
+    deflate_stream.avail_in = uInt(raw.size());
+
+    std::string result;
+    char out[16384];
+
+    int code;
+    do {
+        deflate_stream.next_out = reinterpret_cast<Bytef *>(out);
+        deflate_stream.avail_out = sizeof(out);
+        code = deflate(&deflate_stream, Z_FINISH);
+        if (result.size() < deflate_stream.total_out) {
+            // append the block to the output string
+            result.append(out, deflate_stream.total_out - result.size());
+        }
+    } while (code == Z_OK);
+
+    deflateEnd(&deflate_stream);
+
+    if (code != Z_STREAM_END) {
+        throw std::runtime_error(deflate_stream.msg);
+    }
+
+    return result;
+}
+
+std::string decompress(const std::string &raw) {
+    z_stream inflate_stream;
+    memset(&inflate_stream, 0, sizeof(inflate_stream));
+
+    // TODO: reuse z_streams
+    if (inflateInit(&inflate_stream) != Z_OK) {
+        throw std::runtime_error("failed to initialize inflate");
+    }
+
+    inflate_stream.next_in = (Bytef *)raw.data();
+    inflate_stream.avail_in = uInt(raw.size());
+
+    std::string result;
+    char out[15384];
+
+    int code;
+    do {
+        inflate_stream.next_out = reinterpret_cast<Bytef *>(out);
+        inflate_stream.avail_out = sizeof(out);
+        code = inflate(&inflate_stream, 0);
+        // result.append(out, sizeof(out) - inflate_stream.avail_out);
+        if (result.size() < inflate_stream.total_out) {
+            result.append(out, inflate_stream.total_out - result.size());
+        }
+    } while (code == Z_OK);
+
+    inflateEnd(&inflate_stream);
+
+    if (code != Z_STREAM_END) {
+        throw std::runtime_error(inflate_stream.msg ? inflate_stream.msg : "decompression error");
+    }
+
+    return result;
+}
+}
+}