Siva Velusamy | 0d857b9 | 2015-04-22 10:23:56 -0700 | [diff] [blame] | 1 | package android.view; |
| 2 | |
| 3 | import android.annotation.NonNull; |
| 4 | import android.annotation.Nullable; |
Mathew Inwood | a570dee | 2018-08-17 14:56:00 +0100 | [diff] [blame] | 5 | import android.annotation.UnsupportedAppUsage; |
Siva Velusamy | 0d857b9 | 2015-04-22 10:23:56 -0700 | [diff] [blame] | 6 | |
| 7 | import java.io.ByteArrayOutputStream; |
| 8 | import java.io.DataOutputStream; |
| 9 | import java.io.IOException; |
| 10 | import java.nio.charset.Charset; |
| 11 | import java.util.HashMap; |
| 12 | import java.util.Map; |
| 13 | |
| 14 | /** |
| 15 | * {@link ViewHierarchyEncoder} is a serializer that is tailored towards writing out |
| 16 | * view hierarchies (the view tree, along with the properties for each view) to a stream. |
| 17 | * |
| 18 | * It is typically used as follows: |
| 19 | * <pre> |
| 20 | * ViewHierarchyEncoder e = new ViewHierarchyEncoder(); |
| 21 | * |
| 22 | * for (View view : views) { |
| 23 | * e.beginObject(view); |
| 24 | * e.addProperty("prop1", value); |
| 25 | * ... |
| 26 | * e.endObject(); |
| 27 | * } |
| 28 | * |
| 29 | * // repeat above snippet for each view, finally end with: |
| 30 | * e.endStream(); |
| 31 | * </pre> |
| 32 | * |
| 33 | * <p>On the stream, a snippet such as the above gets encoded as a series of Map's (one |
| 34 | * corresponding to each view) with the property name as the key and the property value |
| 35 | * as the value. |
| 36 | * |
| 37 | * <p>Since the property names are practically the same across all views, rather than using |
| 38 | * the property name directly as the key, we use a short integer id corresponding to each |
| 39 | * property name as the key. A final map is added at the end which contains the mapping |
| 40 | * from the integer to its property name. |
| 41 | * |
| 42 | * <p>A value is encoded as a single byte type identifier followed by the encoding of the |
| 43 | * value. Only primitive types are supported as values, in addition to the Map type. |
| 44 | * |
| 45 | * @hide |
| 46 | */ |
| 47 | public class ViewHierarchyEncoder { |
| 48 | // Prefixes for simple primitives. These match the JNI definitions. |
| 49 | private static final byte SIG_BOOLEAN = 'Z'; |
| 50 | private static final byte SIG_BYTE = 'B'; |
| 51 | private static final byte SIG_SHORT = 'S'; |
| 52 | private static final byte SIG_INT = 'I'; |
| 53 | private static final byte SIG_LONG = 'J'; |
| 54 | private static final byte SIG_FLOAT = 'F'; |
| 55 | private static final byte SIG_DOUBLE = 'D'; |
| 56 | |
| 57 | // Prefixes for some commonly used objects |
| 58 | private static final byte SIG_STRING = 'R'; |
| 59 | |
| 60 | private static final byte SIG_MAP = 'M'; // a map with an short key |
| 61 | private static final short SIG_END_MAP = 0; |
| 62 | |
| 63 | private final DataOutputStream mStream; |
| 64 | |
| 65 | private final Map<String,Short> mPropertyNames = new HashMap<String, Short>(200); |
| 66 | private short mPropertyId = 1; |
| 67 | private Charset mCharset = Charset.forName("utf-8"); |
| 68 | |
| 69 | public ViewHierarchyEncoder(@NonNull ByteArrayOutputStream stream) { |
| 70 | mStream = new DataOutputStream(stream); |
| 71 | } |
| 72 | |
| 73 | public void beginObject(@NonNull Object o) { |
| 74 | startPropertyMap(); |
| 75 | addProperty("meta:__name__", o.getClass().getName()); |
| 76 | addProperty("meta:__hash__", o.hashCode()); |
| 77 | } |
| 78 | |
| 79 | public void endObject() { |
| 80 | endPropertyMap(); |
| 81 | } |
| 82 | |
| 83 | public void endStream() { |
| 84 | // write out the string table |
| 85 | startPropertyMap(); |
| 86 | addProperty("__name__", "propertyIndex"); |
| 87 | for (Map.Entry<String,Short> entry : mPropertyNames.entrySet()) { |
| 88 | writeShort(entry.getValue()); |
| 89 | writeString(entry.getKey()); |
| 90 | } |
| 91 | endPropertyMap(); |
| 92 | } |
| 93 | |
Mathew Inwood | a570dee | 2018-08-17 14:56:00 +0100 | [diff] [blame] | 94 | @UnsupportedAppUsage |
Siva Velusamy | 0d857b9 | 2015-04-22 10:23:56 -0700 | [diff] [blame] | 95 | public void addProperty(@NonNull String name, boolean v) { |
| 96 | writeShort(createPropertyIndex(name)); |
| 97 | writeBoolean(v); |
| 98 | } |
| 99 | |
| 100 | public void addProperty(@NonNull String name, short s) { |
| 101 | writeShort(createPropertyIndex(name)); |
| 102 | writeShort(s); |
| 103 | } |
| 104 | |
Mathew Inwood | a570dee | 2018-08-17 14:56:00 +0100 | [diff] [blame] | 105 | @UnsupportedAppUsage |
Siva Velusamy | 0d857b9 | 2015-04-22 10:23:56 -0700 | [diff] [blame] | 106 | public void addProperty(@NonNull String name, int v) { |
| 107 | writeShort(createPropertyIndex(name)); |
| 108 | writeInt(v); |
| 109 | } |
| 110 | |
Mathew Inwood | a570dee | 2018-08-17 14:56:00 +0100 | [diff] [blame] | 111 | @UnsupportedAppUsage |
Siva Velusamy | 0d857b9 | 2015-04-22 10:23:56 -0700 | [diff] [blame] | 112 | public void addProperty(@NonNull String name, float v) { |
| 113 | writeShort(createPropertyIndex(name)); |
| 114 | writeFloat(v); |
| 115 | } |
| 116 | |
Mathew Inwood | a570dee | 2018-08-17 14:56:00 +0100 | [diff] [blame] | 117 | @UnsupportedAppUsage |
Siva Velusamy | 0d857b9 | 2015-04-22 10:23:56 -0700 | [diff] [blame] | 118 | public void addProperty(@NonNull String name, @Nullable String s) { |
| 119 | writeShort(createPropertyIndex(name)); |
| 120 | writeString(s); |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * Writes the given name as the property name, and leaves it to the callee |
| 125 | * to fill in value for this property. |
| 126 | */ |
| 127 | public void addPropertyKey(@NonNull String name) { |
| 128 | writeShort(createPropertyIndex(name)); |
| 129 | } |
| 130 | |
| 131 | private short createPropertyIndex(@NonNull String name) { |
| 132 | Short index = mPropertyNames.get(name); |
| 133 | if (index == null) { |
| 134 | index = mPropertyId++; |
| 135 | mPropertyNames.put(name, index); |
| 136 | } |
| 137 | |
| 138 | return index; |
| 139 | } |
| 140 | |
| 141 | private void startPropertyMap() { |
| 142 | try { |
| 143 | mStream.write(SIG_MAP); |
| 144 | } catch (IOException e) { |
| 145 | // does not happen since the stream simply wraps a ByteArrayOutputStream |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | private void endPropertyMap() { |
| 150 | writeShort(SIG_END_MAP); |
| 151 | } |
| 152 | |
| 153 | private void writeBoolean(boolean v) { |
| 154 | try { |
| 155 | mStream.write(SIG_BOOLEAN); |
| 156 | mStream.write(v ? 1 : 0); |
| 157 | } catch (IOException e) { |
| 158 | // does not happen since the stream simply wraps a ByteArrayOutputStream |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | private void writeShort(short s) { |
| 163 | try { |
| 164 | mStream.write(SIG_SHORT); |
| 165 | mStream.writeShort(s); |
| 166 | } catch (IOException e) { |
| 167 | // does not happen since the stream simply wraps a ByteArrayOutputStream |
| 168 | } |
| 169 | } |
| 170 | |
| 171 | private void writeInt(int i) { |
| 172 | try { |
| 173 | mStream.write(SIG_INT); |
| 174 | mStream.writeInt(i); |
| 175 | } catch (IOException e) { |
| 176 | // does not happen since the stream simply wraps a ByteArrayOutputStream |
| 177 | } |
| 178 | } |
| 179 | |
| 180 | private void writeFloat(float v) { |
| 181 | try { |
| 182 | mStream.write(SIG_FLOAT); |
| 183 | mStream.writeFloat(v); |
| 184 | } catch (IOException e) { |
| 185 | // does not happen since the stream simply wraps a ByteArrayOutputStream |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | private void writeString(@Nullable String s) { |
| 190 | if (s == null) { |
| 191 | s = ""; |
| 192 | } |
| 193 | |
| 194 | try { |
| 195 | mStream.write(SIG_STRING); |
| 196 | byte[] bytes = s.getBytes(mCharset); |
| 197 | |
| 198 | short len = (short)Math.min(bytes.length, Short.MAX_VALUE); |
| 199 | mStream.writeShort(len); |
| 200 | |
| 201 | mStream.write(bytes, 0, len); |
| 202 | } catch (IOException e) { |
| 203 | // does not happen since the stream simply wraps a ByteArrayOutputStream |
| 204 | } |
| 205 | } |
| 206 | } |