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JPGLoader: Use HashMap instead of Vector for storing components

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The JPEG spec allows component IDs to be chosen arbitrarily from the
interval [0, 255]. Storing components in a vector corrupts the decoder
when component IDs are not in the range 0-3. Normally, encoders don't
use IDs outside of that range because JPEG doesn't support more than
4 channels. But since there is a chance that a spec compliant JPEG
would have component IDs outside of [0-3], we should consider replacing
the vector, which enforces serial component access based on component
IDs, with a HashMap<u8, ComponentSpec>.
This commit is contained in:
devashish 2020-11-29 14:22:42 +05:30 • committed by Andreas Kling
parent 0b252c31b2
commit f107c70652
1 changed files with 29 additions and 28 deletions
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57
Libraries/LibGfx/JPGLoader.cpp
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@ -26,6 +26,7 @@
#include <AK/Bitmap.h> #include <AK/Bitmap.h>
#include <AK/ByteBuffer.h> #include <AK/ByteBuffer.h>
#include <AK/HashMap.h>
#include <AK/LexicalPath.h> #include <AK/LexicalPath.h>
#include <AK/MappedFile.h> #include <AK/MappedFile.h>
#include <AK/MemoryStream.h> #include <AK/MemoryStream.h>
@ -35,7 +36,7 @@
#include <LibGfx/JPGLoader.h> #include <LibGfx/JPGLoader.h>
#include <math.h> #include <math.h>
//#define JPG_DEBUG #define JPG_DEBUG
#define JPG_INVALID 0X0000 #define JPG_INVALID 0X0000
@ -142,7 +143,8 @@ struct MacroblockMeta {
}; };
struct ComponentSpec { struct ComponentSpec {
i8 id { -1 }; u8 serial_id { 255 }; // In the interval [0, 3).
u8 id { 0 };
u8 hsample_factor { 1 }; // Horizontal sampling factor. u8 hsample_factor { 1 }; // Horizontal sampling factor.
u8 vsample_factor { 1 }; // Vertical sampling factor. u8 vsample_factor { 1 }; // Vertical sampling factor.
u8 ac_destination_id { 0 }; u8 ac_destination_id { 0 };
@ -205,9 +207,9 @@ struct JPGLoadingContext {
StartOfFrame frame; StartOfFrame frame;
u8 hsample_factor { 0 }; u8 hsample_factor { 0 };
u8 vsample_factor { 0 }; u8 vsample_factor { 0 };
bool has_zero_based_ids { false };
u8 component_count { 0 }; u8 component_count { 0 };
ComponentSpec components[3]; HashMap<u8, ComponentSpec> components;
// ComponentSpec components[3];
RefPtr<Gfx::Bitmap> bitmap; RefPtr<Gfx::Bitmap> bitmap;
u16 dc_reset_interval { 0 }; u16 dc_reset_interval { 0 };
Vector<HuffmanTableSpec> dc_tables; Vector<HuffmanTableSpec> dc_tables;
@ -294,8 +296,8 @@ static Optional<u8> get_next_symbol(HuffmanStreamState& hstream, const HuffmanTa
*/ */
static bool build_macroblocks(JPGLoadingContext& context, Vector<Macroblock>& macroblocks, u8 hcursor, u8 vcursor) static bool build_macroblocks(JPGLoadingContext& context, Vector<Macroblock>& macroblocks, u8 hcursor, u8 vcursor)
{ {
for (u32 cindex = 0; cindex < context.component_count; cindex++) { for (auto it = context.components.begin(); it != context.components.end(); ++it) {
auto& component = context.components[cindex]; ComponentSpec& component = it->value;
if (component.dc_destination_id >= context.dc_tables.size()) if (component.dc_destination_id >= context.dc_tables.size())
return false; return false;
@ -334,8 +336,8 @@ static bool build_macroblocks(JPGLoadingContext& context, Vector<Macroblock>& ma
if (dc_length != 0 && dc_diff < (1 << (dc_length - 1))) if (dc_length != 0 && dc_diff < (1 << (dc_length - 1)))
dc_diff -= (1 << dc_length) - 1; dc_diff -= (1 << dc_length) - 1;
i32* select_component = component.id == 1 ? block.y : (component.id == 2 ? block.cb : block.cr); i32* select_component = component.serial_id == 0 ? block.y : (component.serial_id == 1 ? block.cb : block.cr);
auto& previous_dc = context.previous_dc_values[cindex]; auto& previous_dc = context.previous_dc_values[component.serial_id];
select_component[0] = previous_dc += dc_diff; select_component[0] = previous_dc += dc_diff;
// Compute the AC coefficients. // Compute the AC coefficients.
@ -398,6 +400,7 @@ static Optional<Vector<Macroblock>> decode_huffman_stream(JPGLoadingContext& con
dbg() << "Image height: " << context.frame.height; dbg() << "Image height: " << context.frame.height;
dbg() << "Macroblocks in a row: " << context.mblock_meta.hpadded_count; dbg() << "Macroblocks in a row: " << context.mblock_meta.hpadded_count;
dbg() << "Macroblocks in a column: " << context.mblock_meta.vpadded_count; dbg() << "Macroblocks in a column: " << context.mblock_meta.vpadded_count;
dbg() << "Mblock meta padded total: " << context.mblock_meta.padded_total;
#endif #endif
// Compute huffman codes for DC and AC tables. // Compute huffman codes for DC and AC tables.
@ -546,15 +549,12 @@ static bool read_start_of_scan(InputMemoryStream& stream, JPGLoadingContext& con
stream >> component_id; stream >> component_id;
if (stream.handle_any_error()) if (stream.handle_any_error())
return false; return false;
component_id += context.has_zero_based_ids ? 1 : 0;
if (component_id == context.components[0].id) auto it = context.components.find(component_id);
component = &context.components[0]; if (it != context.components.end()) {
else if (component_id == context.components[1].id) component = &it->value;
component = &context.components[1]; ASSERT(i == component->serial_id);
else if (component_id == context.components[2].id) } else {
component = &context.components[2];
else {
#ifdef JPG_DEBUG #ifdef JPG_DEBUG
dbg() << stream.offset() << String::format(": Unsupported component id: %i!", component_id); dbg() << stream.offset() << String::format(": Unsupported component id: %i!", component_id);
#endif #endif
@ -824,15 +824,13 @@ static bool read_start_of_frame(InputMemoryStream& stream, JPGLoadingContext& co
return false; return false;
} }
for (int i = 0; i < context.component_count; i++) { for (u8 i = 0; i < context.component_count; i++) {
ComponentSpec& component = context.components[i]; ComponentSpec component;
component.serial_id = i;
stream >> component.id; stream >> component.id;
if (stream.handle_any_error()) if (stream.handle_any_error())
return false; return false;
if (i == 0)
context.has_zero_based_ids = component.id == 0;
component.id += context.has_zero_based_ids ? 1 : 0;
u8 subsample_factors = 0; u8 subsample_factors = 0;
stream >> subsample_factors; stream >> subsample_factors;
@ -841,7 +839,7 @@ static bool read_start_of_frame(InputMemoryStream& stream, JPGLoadingContext& co
component.hsample_factor = subsample_factors >> 4; component.hsample_factor = subsample_factors >> 4;
component.vsample_factor = subsample_factors & 0x0F; component.vsample_factor = subsample_factors & 0x0F;
if (component.id == 1) { if (component.serial_id == 0) {
// By convention, downsampling is applied only on chroma components. So we should // By convention, downsampling is applied only on chroma components. So we should
// hope to see the maximum sampling factor in the luma component. // hope to see the maximum sampling factor in the luma component.
if (!validate_luma_and_modify_context(component, context)) { if (!validate_luma_and_modify_context(component, context)) {
@ -871,7 +869,10 @@ static bool read_start_of_frame(InputMemoryStream& stream, JPGLoadingContext& co
#endif #endif
return false; return false;
} }
context.components.set(component.id, component);
} }
return true; return true;
} }
@ -946,14 +947,14 @@ static void dequantize(JPGLoadingContext& context, Vector<Macroblock>& macrobloc
{ {
for (u32 vcursor = 0; vcursor < context.mblock_meta.vcount; vcursor += context.vsample_factor) { for (u32 vcursor = 0; vcursor < context.mblock_meta.vcount; vcursor += context.vsample_factor) {
for (u32 hcursor = 0; hcursor < context.mblock_meta.hcount; hcursor += context.hsample_factor) { for (u32 hcursor = 0; hcursor < context.mblock_meta.hcount; hcursor += context.hsample_factor) {
for (u8 cindex = 0; cindex < context.component_count; cindex++) { for (auto it = context.components.begin(); it != context.components.end(); ++it) {
auto& component = context.components[cindex]; auto& component = it->value;
const u32* table = component.qtable_id == 0 ? context.luma_table : context.chroma_table; const u32* table = component.qtable_id == 0 ? context.luma_table : context.chroma_table;
for (u32 vfactor_i = 0; vfactor_i < component.vsample_factor; vfactor_i++) { for (u32 vfactor_i = 0; vfactor_i < component.vsample_factor; vfactor_i++) {
for (u32 hfactor_i = 0; hfactor_i < component.hsample_factor; hfactor_i++) { for (u32 hfactor_i = 0; hfactor_i < component.hsample_factor; hfactor_i++) {
u32 mb_index = (vcursor + vfactor_i) * context.mblock_meta.hpadded_count + (hfactor_i + hcursor); u32 mb_index = (vcursor + vfactor_i) * context.mblock_meta.hpadded_count + (hfactor_i + hcursor);
Macroblock& block = macroblocks[mb_index]; Macroblock& block = macroblocks[mb_index];
int* block_component = cindex == 0 ? block.y : (cindex == 1 ? block.cb : block.cr); int* block_component = component.serial_id == 0 ? block.y : (component.serial_id == 1 ? block.cb : block.cr);
for (u32 k = 0; k < 64; k++) for (u32 k = 0; k < 64; k++)
block_component[k] *= table[k]; block_component[k] *= table[k];
} }
@ -982,13 +983,13 @@ static void inverse_dct(const JPGLoadingContext& context, Vector<Macroblock>& ma
for (u32 vcursor = 0; vcursor < context.mblock_meta.vcount; vcursor += context.vsample_factor) { for (u32 vcursor = 0; vcursor < context.mblock_meta.vcount; vcursor += context.vsample_factor) {
for (u32 hcursor = 0; hcursor < context.mblock_meta.hcount; hcursor += context.hsample_factor) { for (u32 hcursor = 0; hcursor < context.mblock_meta.hcount; hcursor += context.hsample_factor) {
for (u8 cindex = 0; cindex < context.component_count; cindex++) { for (auto it = context.components.begin(); it != context.components.end(); ++it) {
auto& component = context.components[cindex]; auto& component = it->value;
for (u8 vfactor_i = 0; vfactor_i < component.vsample_factor; vfactor_i++) { for (u8 vfactor_i = 0; vfactor_i < component.vsample_factor; vfactor_i++) {
for (u8 hfactor_i = 0; hfactor_i < component.hsample_factor; hfactor_i++) { for (u8 hfactor_i = 0; hfactor_i < component.hsample_factor; hfactor_i++) {
u32 mb_index = (vcursor + vfactor_i) * context.mblock_meta.hpadded_count + (hfactor_i + hcursor); u32 mb_index = (vcursor + vfactor_i) * context.mblock_meta.hpadded_count + (hfactor_i + hcursor);
Macroblock& block = macroblocks[mb_index]; Macroblock& block = macroblocks[mb_index];
i32* block_component = cindex == 0 ? block.y : (cindex == 1 ? block.cb : block.cr); i32* block_component = component.serial_id == 0 ? block.y : (component.serial_id == 1 ? block.cb : block.cr);
for (u32 k = 0; k < 8; ++k) { for (u32 k = 0; k < 8; ++k) {
const float g0 = block_component[0 * 8 + k] * s0; const float g0 = block_component[0 * 8 + k] * s0;
const float g1 = block_component[4 * 8 + k] * s4; const float g1 = block_component[4 * 8 + k] * s4;