Getintrinsicheight () and getintrinsicwidth () of drawable ()

Today I encountered a problem where a bitmap is encapsulated into bitmapdrawable, bitmapdrawable drawable = new bitmapdrawable (BMP ),

Bitmap. getwidth ()! = Bitmapdrawable. getintrinsicwidth (). Some problems are caused:

Check the source code. The problem is as follows:

In bitmapdrawable, when assigning values to mbitmapwidth, you must scale the value according to the density. The default value is 160, and the mdpi is used:

Mtargetdensity = displaymetrics. density_default;

In the case that the density of bitmap is 240, the scaling is:

The formula is approximately equal to: drawabledensity * BMP width/BMP density ====>> 160*72/240, so getintrinsicheight () is 48

In bitmapdrawable:

  private void computeBitmapSize() {        mBitmapWidth = mBitmap.getScaledWidth(mTargetDensity);        mBitmapHeight = mBitmap.getScaledHeight(mTargetDensity);    }

 @Override    public int getIntrinsicWidth() {        return mBitmapWidth;    }    @Override    public int getIntrinsicHeight() {        return mBitmapHeight;    }

private BitmapDrawable(BitmapState state, Resources res) {        mBitmapState = state;        if (res != null) {            mTargetDensity = res.getDisplayMetrics().densityDpi;        } else if (state != null) {            mTargetDensity = state.mTargetDensity;        } else {            mTargetDensity = DisplayMetrics.DENSITY_DEFAULT;        }        setBitmap(state.mBitmap);    }

In buttonstate, the default value of mtargetdensity is:

Int mtargetdensity = displaymetrics. density_default;

Note: When res = NULL, and state! = NULL, mtargetdensity = state. mtargetdensity;

 /**     * Create an empty drawable, setting initial target density based on     * the display metrics of the resources.     */    public BitmapDrawable(Resources res) {        mBitmapState = new BitmapState((Bitmap) null);        mBitmapState.mTargetDensity = mTargetDensity;    }    /**     * Create drawable from a bitmap, not dealing with density.     * @deprecated Use {@link #BitmapDrawable(Resources, Bitmap)} to ensure     * that the drawable has correctly set its target density.     */    @Deprecated    public BitmapDrawable(Bitmap bitmap) {        this(new BitmapState(bitmap), null);    }

    /**     * Create drawable from a bitmap, setting initial target density based on     * the display metrics of the resources.     */    public BitmapDrawable(Resources res, Bitmap bitmap) {        this(new BitmapState(bitmap), res);        mBitmapState.mTargetDensity = mTargetDensity;    }

Bitmapdrawable (bitmap BMP) has been discarded. If bitmapdrawable (bitmap BMP, resources res) is used

In displaymetrics:

 public static final int DENSITY_DEFAULT = DENSITY_MEDIUM;

In bitmap:

   /**     * Convenience method that returns the width of this bitmap divided     * by the density scale factor.     *     * @param targetDensity The density of the target canvas of the bitmap.     * @return The scaled width of this bitmap, according to the density scale factor.     */    public int getScaledWidth(int targetDensity) {        return scaleFromDensity(getWidth(), mDensity, targetDensity);    }    /**     * Convenience method that returns the height of this bitmap divided     * by the density scale factor.     *     * @param targetDensity The density of the target canvas of the bitmap.     * @return The scaled height of this bitmap, according to the density scale factor.     */    public int getScaledHeight(int targetDensity) {        return scaleFromDensity(getHeight(), mDensity, targetDensity);    }        /**     * @hide     */    static public int scaleFromDensity(int size, int sdensity, int tdensity) {        if (sdensity == DENSITY_NONE || sdensity == tdensity) {            return size;        }                // Scale by tdensity / sdensity, rounding up.        return ( (size * tdensity) + (sdensity >> 1) ) / sdensity;    }

In this case, only the following changes are made:

Method 1:

Bitmapdrawable BMP drawable = new bitmapdrawable (BMP, getresources );

Method 2:

Bitmapdrawable BMP drawable = new bitmapdrawable (BMP );

BMP drawable. settargetdensity (getresources (). getresources (). getdisplaymetrics ());